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TRANSACTIONS  OF  THE 

CONNECTICUT  ACADEMY  OF  ARTS  AND  SCIENCES 

Incorporated  A.  D.  1799 

YOLDME  22,  PAGES  249  -467  JUNE,  1918 


The  Vegetation 

OF 

Northern  Cape  Breton  Island, 
Nova  Scotia 


GEORGE  E.  NICHOLS,  Ph.D., 

Assistant  Professor  of  Botany  in  the  Sheffield  Scientific  School 
of  Yale  University 


YALE  UNIVERSITY  PRESS 

NEW  HAVEN,  CONNECTICUT 


1918 


THE  TUTTLE,  MOREHOUSE  & TAYLOR  COMPANY 


Sc SI -37/ 6 
N 6/3  V 


Biology  Library 

CONTENTS 


Page 

INTRODUCTION  257 

I.  GENERAL  PHYTOGEOGRAPHIC  RELATIONS  OF  THE 

REGION  ' 257 

II.  PREVIOUS  BOTANICAL  INVESTIGATIONS,  AND 

FIELD  WORK  OF’THE  AUTHOR  261 

III.  ACKNOWLEDGMENTS  263 

IV.  PHYSIOGRAPHY  263 

V.  CLIMATE  269 

VI.  ECOLOGICAL  CLASSIFICATION  OF  MATERIAL; 

NOMENCLATURE  274 

THE  DECIDUOUS  FOREST  CLIMATIC  FORMATION  IN 

NORTHERN  CAPE  BRETON  278 

I.  THE  REGIONAL  CLIMAX  ASSOCIATION-TYPE:  THE 

CLIMAX  FOREST  278 

II.  THE  EDAPHIC  FORMATION-COMPLEX  OF  THE 

REGION  294 

A.  Primary  Formations  of  the  Xerarch  Series  294 

1.  The  Formation-types  of  Ordinary  Uplands  ....'. 294 

a.  Introductory  294 

b.  The  Association-complexes  of  Rock  Outcrops  295 

c.  The  Association-complexes  of  Glacial  Drift  300 

d.  The  Association-complexes  of  Talus  302 

2.  The  Formation-types  of  Coplands  along  Streams  306 

a.  Introductory  306 

b.  The  Association-complexes  of  Rock  Ravines  309 

c.  The  Association-complexes  of  Open  Valleys  314 

d.  The  Association-complexes  of  Boulder  Plains  315 

e.  The  Association-complexes  of  Flood  Plains 317 

3.  The  Formation-types  of  Uplands  along  the  Seacoast  . . . 319 

a.  Introductory  319 

b.  The  Association-complexes  of  Sea  Bluffs  and  Head- 

lands   319 

c.  The  Association-complexes  of  Beaches  and  Dunes  . . 324 


3*70924 


252  Contents. 

Page 

B.  Secondary  Formations  of  the  Xerarch  Series  334 

Formation-types  resulting  primarily  from  Human  Activity  334 

a.  Association-complexes  due  to  Cultivation  334 

b.  Association-complexes  due  to  Fire  341 

c.  Association-complexes  due  to  Logging  346 

C.  Primary  Formations  of  the  Hydrarch  Series  347 

1.  The  Formation-types  of  Lakes  and  Ponds  Inland 347 

a.  Introductory  347 

b.  The  Association-complexes  of  Well-drained  Lakes 

and  Ponds  350 

c.  The  Association-complexes  of  Undrained  Lakes  and 

Ponds  353 

2.  The  Formation-types  of  Lake-  and  Spring-swamps 

Inland 354 

a.  Introductory  354 

b.  The  Association-complexes  of  Well-drained  Swamps  356 

c.  The  Association-complexes  of  Undrained  Swamps  ..  359 

d.  The  Association-complexes  of  Poorly  Drained  Swamps  364 

3.  The  Formation-types  in  and  along  Rivers  and  Streams  368 

a.  Introductory  368 

b.  The  Association-complexes  of  Ravines  369 

c.  The  Association-complexes  of  Flood  Plains  371 

4.  The  Formation-types  along  the  Seacoast  374 

a.  Introductory  374 

b.  The  Association-complexes  of  Salt  and  Brackish 

Lakes  and  Ponds  375 

c.  The  Association-complexes  of  Salt  Marshes 376 

d.  The  Association-complexes  of  Brackish  Marshes  ...  379 

D.  Secondary  Formations  of  the  Hydrarch  Series  383 

Formation- types  resulting  primarily  from  Human  Activity  383 

Association-complexes  due  to  Various  Agencies  383 

THE  NORTHEASTERN  EVERGREEN  CONIFEROUS  FOR- 
EST CLIMATIC  FORMATION  IN  NORTHERN  CAPE 
BRETON  385 

I.  GENERAL  CONSIDERATIONS  385 

II.  THE  REGIONAL  CLIMAX  ASSOCIATION-TYPE:  THE 

CLIMAX  FOREST  389 

III.  THE  EDAPHIC  FORMATION-COMPLEX  OF  THE  RE- 
GION   395 


Contents. 


253 


Page 

A.  Preliminary  Observations  395 

B.  Formations  .of  the  Xerarch  Series  396 

1.  The  Formation-types  of  Ordinary  Uplands  in  the  For- 

ested Region  396 

a.  The  Association-complexes  of  Well-drained  Uplands  396 

b.  The  Association-complexes  of  Poorly  Drained  Up- 

lands   397 

2.  The  Formation-types  of  Ordinary  Uplands  in  the  Barrens  399 

a.  The  Association-complexes  of  Well-drained  Uplands  399 

b.  The  Association-complexes  of  Poorly  Drained  Up- 

lands   413 

3.  The  Formation-types  of  Uplands  along  Streams  414 

The  Association-complexes  of  Ravines  and  Valleys  ....  414 

C.  Formations  of  the  Hydrarch  Series  415 

1.  The  Formation-types  of  Lakes  and  Ponds  415 

a.  Introductory  415 

b.  The  Association-complexes  of  Well-drained  Lakes 

and  Ponds  416 

c.  The  Association-complexes  of  Undrained  Ponds  ....  417 

2.  The  Formation-types  of  Lake-,  Spring-,  and  Precipita-  ' 

tion-swamps  418 

a.  The  Association-complexes  of  Well-drained  Swamps  418 

b.  The  Association-complexes  of  Poorly  Drained  Swamps  419 

c.  The  Association-complexes  of  Undrained  Swamps  . . 422 

d.  The  Association-complexes  of  Raised  Bogs  433 

3.  The  Formation-types  of  Swamps  along  Streams  456 

The  Association-complexes  of  Ravines  and  Flood  Plains  456 

SUMMARY  459 

BIBLIOGRAPHY  463 

INDEX  OF  TABLES 

I.  Temperature  and  precipitation  records  at  Sydney,  Nova  Scotia  270 

II.  Temperature  and  precipitation  data  at  selected  stations  in 

eastern  Canada  270 

III.  Evaporation  rate  along  the  coast  in  northern  Cape  Breton  272 

IV.  Temperature  in  the  interior  and  along  the  coast  of  northern 

Cape  Breton  v 273 

V.  Quadrat  studies  in  hardwood  forest;  Barrasois  286 

VI.  Evaporation  rate  in  various  habitats ; Barrasois  314 


390924 


254 


Contents. 


LIST  OF  FIGURES 

Page 

1.  Map  of  eastern  North  America,  showing  position  of  Cape  Breton 

with  reference  to  the  Transition  Forest  Region  258 

2.  Map  of  northern  Cape  Breton,  showing  distribution  of  forest 

regions  and  barrens  260 

3.  Lowland  and  plateau,  viewed  from  Middle  Head,  Ingonish  264 

4.  View  across  forested  portion  of  plateau  265 

5.  View  southward  along  coast  from  near  summit  of  Smoky  266 

6.  Ingonish  Harbor  and  Mt.  Smoky  ' 266 

7.  Lower  end  of  Big  Intervale,  Aspy  Bay  267 

8.  Mountains  and  lowland  along  coast  north  of  Cheticamp  268 

9.  Second  growth  woodland  in  lowland ; Barrasois  278 

10.  Primeval  climax  forest;  Northeast  Margaree  279 

11.  Primeval  climax  forest;  Indian  Brook  281 

12.  Primeval  climax  forest;  Barrasois  282 

13.  Balsam  fir  wind-fall;  Adirondacks,  New  York  290 

14.  Granitic  talus,  north  of  Cheticamp  302 

15.  Gypsum  outcrop  along  Ingonish  Harbor  305 

16.  Pioneer  growth  of  white  spruce  on  granitic  talus ; Barrasois  . . 306 

17.  Valley  along  lower  course  of  Barrasois  River  307 

18.  Boulder  plain  along  Barrasois  River  308 

19.  Gorge  along  Indian  Brook  310 

20.  Upper  end  of  Big  Intervale,  Aspy  Bay  313 

21.  Boulder  plains  and  flood  plains  along  Middle  River  316 

22.  Juniperus  horisontalis  on  sea  bluff ; Middle  Head,  Ingonish  . . . 320 

23.  Alnus  mollis  and  Picea  canadensis  on  clay  sea  bluff ; Cape  North  321 

24.  Exposed  headland ; White  Point  322 

25.  Vegetation  on  exposed  headland;  White  Point  323 

26.  Shingle  beach  enclosing  fresh  pond ; Wreck  Cove  325 

27.  Shingle  beach ; Barrasois  326 

28.  Spit  with  sand  and  shingle ; Barrasois  327 

29.  Stunted  firs  on  shingle  beach ; Barrasois  329 

30.  Sand  spit  at  Aspy  Bay  330 

31.  Sand  dunes  with  Picea  canadensis;  Aspy  Bay  331 

32.  Sand  dunes  with  Poa  compressa ; Aspy  Bay  332 

33.  Abandoned  pastures,  etc.,  along  St.  Ann’s  Baj'  334 

34.  Abandoned  field  with  white  spruce  and  Dicksonia;  Barrasois  336 

35.  Fir  and  spruce  reproduction  in  abandoned  field;  Barrasois  337 

36.  Grove  of  white  spruce  in  abandoned  pasture;  Barrasois  339 

37.  Forest  succession  in  a burned  area;  Maine 342 

38.  Barrens  and  second  growth  forests  along  coast  north  of  Neil’s 

Harbor  343 

39.  White  spruce  reproduction  after  cutting  and  burning;  Ingonish  344 

40.  Blueberry  barren  near  Frizzleton  345 

41.  Freshwater  Lake;  South  Bay,  Ingonish  349 

42.  Fresh  pond  behind  shingle  beach ; Barrasois  351 


Contents. 


255 


Page 


43.  Bog  near  mouth  of  Barrasois  River  360 

44.  Diagrammatic  sections  of  poorly  drained  swamps ; Broadcove 

Mountain  365 

45.  Salt  marsh ; Aspy  Bay  377 

46.  Brackish  marsh ; Barrasois  380 

47.  Primeval  coniferous  forest  in  mountains  near  Cape  North  386 

48.  Barrens  in  mountains  north  of  Barrasois  ; 388 

49.  Primeval  coniferous  forest  in  mountains  north  of  Barrasois  ....  390 

50.  Low  coniferous  woodland  on  plateau  397 

51.  General  view  of  barrens,  with  heath,  etc 398 

52.  Dwarf  shrub-spruce  heath  in  barrens  401 

53.  Hummock  in  dwarf  shrub-spruce  heath  403 

54.  Kruntmholz  and  low  woodland  in  barrens  406 

55.  Low  Krummholz  association-type  in  barrens  407 

56.  Gnarled  tamaracks  on  exposed  summit  in  barrens  409 

57.  Habit  sketch  of  balsam  fir,  growing  in  forest  scrub  410 

58.  Weather  beaten  balsam  fir  in  barrens  412 

59.  Ravine  forest  in  barrens  414 

60.  Small  lake  in  mountains ; aquatic  vegetation  and  narrow  mar- 

ginal fringe  of  swamp  shrubs  416 

61.  Small  lake  in  mountains  with  border  of  marshy  swamp  420 

62.  Undrained  pool,  with  marginal  vegetation,  in  raised  bog  in 

barrens  427 

63.  Characteristic  mountain  bog 431 

64.  Raised  bog ; Peter’s  Barren  433 

65.  Diagrammatic  representation  of  bog  complex  in  barrens  437 

66.  Raised  bog  in  barrens  438 

67.  Wet  bog  and  bog  meadow  in  shallow  valley  in  barrens  442 

68.  Wet  bog  and  forest  scrub  in  barrens  444 

69.  Pools  on  surface  of  raised  bog  in  barrens  454 

70.  Shallow,  flat-floored  stream  valley  in  barrens  457 


INTRODUCTION 


I.  GENERAL  PHYTOGEOGRAPHIC  RELATIONS  OF  THE 

REGION 

Viewed  from  the  standpoint  of  ecological  plant  geography,  the 
vegetation  of  the  forested  portions  of  eastern  North  America, 
north  of  southern  Florida,  comprises  two  great  climatic  forma- 
tions : the  Deciduous  Forest  Formation  and  the  Northeastern 
Evergreen  Coniferous  Forest  Formation.  Viewed  from  the 
standpoint  of  floristic  plant  geography,  it  is  possible  to  subdivide 
the  vegetation  of  this  area  still  further  (in  this  connection  see 
especially  Transeau  ’05,  Harshberger  Ti,  Shreve  ’17),  but  from 
the  ecological  point  of  view,  as  will  be  emphasized  later,  the 
advisability  of  such  subdivision  is  at  least  open  to  question. 

The  deciduous  forest  formation  attains  its  highest  and  most 
typical  development  in  the  lower  Ohio  basin  and  the  southern 
Appalachians,  where  the  climax  forests  are  made  up  almost  wholly 
of  deciduous  trees.  These  include  a wealth  of  species,  prominent 
among  which  are  beech  (Fagus  grandifolia ) and  sugar  maple 
( Acer  saccharum),  chestnut  ( Castanea  dentata)  and  tulip 
(Liriodendron  Tulipifera) , red  oak  ( Quercus  rubra),  white  oak 
{Quercus' alba) , hickory  (especially  Carya  alba),  and  white  ash 
( Fraxinus  americana) . The  evergreen  coniferous  forest  forma- 
tion attains  its  optimum  development  in  middle-eastern  Canada. 
Here  the  climax  forests  are  relatively  poor  in  species,  consisting 
mainly  of  balsam  fir  ( Abies  balsamea) , white  spruce  ( Picea  cana- 
densis) and  black  spruce1  ( Picea  mariana),  with  which  is  asso- 
ciated the  paper  birch  ( B etui  a alba  papyrifera) . 


1 In  all  the  current  manuals  a distinction  is  made  between  the  black 
spruce  and  the  red  spruce  ( Picea  rubra).  After  several  years  of  experi- 
ence in  the  north-woods,  the  writer  is  obliged  to  confess  his  inability  to 
differentiate  with  certainty  between  the  two,  an  inability  which  he  finds 
to  be  shared  by  many  other  botanists.  It  is  his  opinion  that  the  red  spruce 
at  best  should  be  regarded  merely  as  a variety  of  the  black  spruce,  the 
status  which  it  formerly  held.  To  be  sure,  the  small,  impoverished  bog 
form  of  this  tree  (the  typical  P.  mariana  of  the  manuals)  does  appear  very 
distinct  when  compared  with  the  large,  thrifty  upland  form  (which  typi- 
fies P.  rubra)  ; but  there  are  all  sorts  of  intergradations  between  these  two 


258 


George  E.  Nichols, 


Midway  between  these  two  regions  (see  map,  Fig.  i),  is 
situated  the  Transition  Forest  Region,  a broad  zone  in  which,  due 
to  the  overlap  in  the  ranges  of  the  southern  and  northern  climax 


Figure  i. — Map  of  eastern  North  America,  to  show  position  of  Cape 
Breton  Island  with  reference  to  the  Transition  Forest  Region. 


extremes.  Moreover,  especially  in  these  intermediate  forms,  the  struc- 
tural dissimilarities  upon  which  the  manuals  lay  stress  in  attempting  to 
differentiate  two  distinct  species,  are  far  from  satisfactory  in  their  applica- 
tion. In  the  present  paper  no  attempt  is  made  to  distinguish  P.  rubra 
from  P.  mariana,  although  it  is  appreciated  that  much  of  the  upland 
spruce  may  perhaps  well  be  referred  to  the  former  “species.” 


Vegetation  of  Northern  Cape  Breton.  259 

trees,  the  nature  of  the  climax  forest,  taken  in  its  entirety,  is 
intermediate  between  that  of  the  evergreen  coniferous,  and  that 
of  the  deciduous  climatic  formation,  as  most  typically  developed: 
where,  in  other  words,  the  two  formations  are  telescoped.  This 
region  represents  a great  tension  zone,  in  which  competition 
between  the  northern  and  southern  climax  trees  is  still  in  active 
progress,  and  where,  as  a result,  it  is  possible  to  study  the 
ecological  relations  of  the  two  groups  of  species  concerned.  The 
northern  boundary  of  this  transition  region  is  determined  by  the 
northern  outposts  of  the  deciduous  climax  trees  of  the  deciduous 
forest  formation  : it  may  be  regarded  as  coinciding  approximately 
with  the  northern  limit  of  the  sugar  maple  (see,  in  this  connec- 
tion, Cooper  ’13,  pp.  36-39).  In  the  same  way,  the  southern 
boundary  of  the  transition  region  may  be  said  to  be  determined 
by  the  southern  outposts  of  the  climax  trees  of  the  evergreen 
coniferous  forest  formation,  in  so  far  as  these  grow  on  uplands : 
it  may  be  regarded  as  coinciding  roughly  with  the  southern  limit 
of  the  balsam  fir.  These  boundaries  are  indicated  on  the  map 
(Fig.  i),  but  the  lines  as  drawn  can  represent  little  more  than  a 
rough  approximation ; for,  owing  largely  to  variations  in  topog- 
raphy, at  higher  elevations  the  evergreen  coniferous  forest 
formation  locally  extends  far  to  the  south  of  the  northern 
boundary,  while  at  lower  elevations  the  deciduous  forest  forma- 
tion is  typically  developed  considerable  distances  north  of  the 
southern  boundary  of  the  transition  region,  as  here  represented. 

From  the  standpoint  of  floristic  plant  geography  it  is  signifi- 
cant that  the  geographic  center  of  distribution  for  the  so-called 
Canadian  element  in  the  flora  of  eastern  North  America  lies 
within  this  transition  region.  Many  Canadian  species  are  practi- 
cally confined  to  this  area,  prominent  examples  of  this  latter 
group,  among  the  woody  plants,  being  Pinus  Strobus  and  P. 
resinosa,  Tsuga  canadensis,  Betula  lutea,  Acer  pennsylvanicum, 
and  Viburnum  alnifolium.  But  while,  from  the  floristic  point  of 
view,  the  vegetation  of  this  region  certainly  is  more  or  less  unique, 
from  an  ecological  point  of  view  it  is  doubtfully  to  be  regarded 
as  a distinct  climatic  formation.  And  while  its  intermediate 
character  is  generally  recognized,  nevertheless,  largely  because  of 
the  almost  universal  supremacy,  in  situations  edaphically  favora- 
ble to  their  development,  of  the  climax  trees  of  the  deciduous 
forest  formation  over  those  of  the  northeastern  evergreen  conifer- 


260 


George  E.  Nichols, 


Figure  2. — Map  of  northern  Cape  Breton,  showing  approximate  dis- 
tribution of  deciduous  forest  climatic  formation  and  northeastern  ever- 
green coniferous  forest  climatic  formation.  The  unshaded  areas  are  very 
largely  occupied  by  barrens.  Inserted  map  : Cape  Breton  Island,  together 
with  a small  portion  of  the  peninsula  of  Nova  Scotia. 


Vegetation  of  Northern  Cape  Breton.  261 

ous  forest  formation,  wherever  these  two  groups  come  into 
competition  with  one  another,  from  the  standpoint  of  ecological 
plant  geography  it  seems  best,  on  the  whole,  to  regard  the  vegeta- 
tion of  this  transition  region  as  constituting  merely  the  northward 
extension  of  the  deciduous  forest  formation. 

As  a glance  at  the  map  (Fig.  i)  will  show,  Cape  Breton  Island, 
located  northeast  of  the  peninsula  of  Nova  Scotia  (lat.  45 0 30'- 
470  N. ; long.  6o°  I5'-6i°  30'  and  separated  from  the  main- 
land only  by  the  Gut  of  Canso,  a narrow  strait  scarcely  a mile 
wide,  is  situated  near  the  northern  edge  of  the  transition  forest 
region.  In  northern  Cape  Breton,  owing  chiefly  to  differences 
in  climate  at  different  elevations,  both  the  deciduous  forest  forma- 
tion and  the  northeastern  evergreen  coniferous  forest  formation 
are  well  represented : the  former  predominates  from  sea  level  up 
to  an  altitude  of  about  700  feet;  the  latter  prevails  at  higher 
elevations.  The  approximate  distribution  in  this  region  of  these 
two  formations  is  mapped  in  Fig.  2.  The  vegetation  of  the  Bar- 
rens, which  occupy  the  highest  parts  of  the  plateau,  apparently 
bears  much  the  same  relationship  to  the  evergreen  coniferous 
forest  formation  on  the  one  hand  and  the  arctic  tundra  on  the 
other  that  the  vegetation  of  the  transition  forest  region  bears  to 
the  deciduous  forest  formation  and  the  evergreen  coniferous 
forest  formation  respectively : it  seems  to  represent  a transition 
between  evergreen  coniferous  forest,  as  typically  developed,  and 
tundra.  For  various  reasons  the  barrens  have  been  mapped  as 
distinct,  but  their  vegetation  is  to  be  regarded  merely  as  the 
upward  extension  of  the  evergreen  coniferous  forest  formation. 


II.  PREVIOUS  BOTANICAL  INVESTIGATIONS,  AND  FIELD 
WORK  OF  THE  AUTHOR 

Aside  from  the  work  of  Ganong  (’91,  ’93,  etc.)  and  Transeau 
(’09),  practically  no  investigations  of  a purely  ecological  nature 
have  been  conducted  in  the  Maritime  Provinces  of  eastern 
Canada  (New  Brunswick  and  Nova  Scotia).  The  present  paper 
aims  to  portray  in  a general  way  the  ecological  relations  of  the 
vegetation  in  a portion  of  this  area. 

So  far  as  is  known  to  the  writer,  only  three  other  botanists — 
John  Macoun  (’83-02,  ’98),  C.  B.  Robinson  (’03,  ’04,  etc.),  and 


262 


George  E.  Nichols, 


J.  R.  Churchill — have  undertaken  any  explorations  in  northern 
Cape  Breton.  Aside  from  the  work  of  these  three,  which  was 
almost  wholly  taxonomic,  scattered  observations  of  general  botani- 
cal interest  are  recorded  in  the  report  on  the  geology  of  this  region 
(’85)  by  Hugh  Fletcher,  the  pioneer  geologist  whose  detailed 
maps,  constructed  more  than  thirty  years  ago,  have  afforded  the 
basis  for  all  subsequent  explorations;  while  B.  E.  Fernow,  on  the 
basis  of  a survey  made  for  commercial  purposes,  has  briefly 
described  the  forests  here,  with  an  accompanying  map,  in  his 
account  of  the  forest  conditions  of  Nova  Scotia  (’12). 

The  writer’s  acquaintance  with  northern  Cape  Breton  dates 
back  to  1905  when  about  three  weeks  were  occupied  in  a tramp 
along  the  coast  from  Baddeck  to  Ingonish,  across  the  island  from 
North  River  to  Northeast  Margaree,  and  thence  back  to  Baddeck. 
It  was  on  this  trip  that  the  curly  grass  fern  ( Schizaea  pusilla) 
was  first  recorded  from  Cape  Breton  (see  Nichols  ’05).  In 
1909,  a month  was  spent  in  camp  near  the  mouth  of  the  Barrasois 
River,  but  beyond  the  collection  and  identification  of  mosses  and 
liverworts  no  serious  botanical  work  was  attempted.  The  investi- 
gations embodied  in  the  present  paper  were  projected  in  1913  and 
have  been  carried  on  for  parts  of  four  summers.  Altogether, 
during  this  time,  more  than  six  months  have  been  occupied  by 
field  work  in  northern  Cape  Breton.  In  1914,  and  again  in  1915, 
a base  camp  was  maintained  for  about  a month  along  the  lower 
course  of  the  Barrasois  River  (St.  Ann’s),  from  which  point 
excursions  were  made  into  the  surrounding  country,  while  another 
month  was  spent  at  various  points  along  the  eastern  coast,  between 
St.  Ann’s  Bay  and  Aspy  Bay,  and  in  the  interior.  During  the 
summer  of  1916  the  entire  length  of  the  coast  from  St.  Ann’s  Bay 
to  Cape  North  was  traversed  on  foot,  and  a week  was  spent  in  the 
interior.  On  this  trip  the  writer  was  accompanied  by  Dr.  L.  H. 
Harvey,  whose  experience  in  the  Mt.  Ktaadn  region  suggested 
many  interesting  comparisons.  The  first  draft  of  the  present 
paper  was  preparedduring  the  college  year  1916-1917,  and  in  the 
summer  of  1917  another  month  was  spent  in  the  field,  partly  for 
the  purpose  of  checking  up  previous  observations,  partly  with  the 
object  of  visiting  the  western  coast  of  the  area  under  considera- 
tion. On  this  trip,  starting  from  Baddeck,  the  author  traveled 
to  Middle  River,  Northeast  Margaree  and  Margaree  Harbor, 
thence  along  the  coast  to  Cheticamp  and  Pleasant  Bay,  across  the 


Vegetation  of  Northern  Cape  Breton.  263 

island  to  Aspy  Bay,  and  from  here  to  Ingonish,  from  which  point 
another  excursion  was  made  into  the  interior. 

As  a desirable  adjunct  to  the  ecological  investigations,  con- 
siderable attention  has  been  devoted  to  the  flora  of  the  region : 
two  papers  on  the  bryophytes  of  Cape  Breton  have  already  been 
published  (T6a,  ’18),  and  a-  similar  catalogue  of  the  vascular 
plants  is  contemplated.  Incidentally,  in  addition  to  the  studies  in 
northern  Cape  Breton,  the  writer  has  recently  visited  two  other 
widely  separated  areas  within  the  transition  region : in  the  spring 
of  1916  a week  was  spent  at  the  Yale  Forest  School  Camp  near 
Brandreth,  in  the  western  Adirondacks ; while  during  the  sum- 
mer of  1917  nearly  a month  was  occupied,  in  company  with  Dr. 
Harold  St.  John  of  the  Gray  Herbarium,  in  exploring  the  upper 
waters  of  the  St.  John  River,  in  northwestern  Maine.  Also,  in 
connection  with  the  study  of  raised  bogs  in  northern  Cape  Breton, 
a visit  was  made,  in  1917,  to  one  of  the  New  Brunswick  bogs 
described  by  Ganong  (’91,  ’97). 

III.  ACKNOWLEDGMENTS 

The  writer  wishes  to  express  his  indebtedness  to  Professor 
Alexander  W.  Evans  for  his  continued  interest  in  this  work 
throughout  its  progress ; to  Mr.  Albert  F.  Hill,  Professor  Merritt 
L.  Fernald,  Dr.  Harold  St.  John,  and  Mr.  Charles  A.  Weatherby, 
who  have  determined  or  passed  judgment  on  the  vascular  plants 
collected;  to  Professors  A.  Le  Roy  Andrews  and  Lincoln  W. 
Riddle,  who  have  determined  the  sphagnums  and  lichens  respec- 
tively; and  to  various  others  (see  Nichols  T6a),  who  have  assisted 
in  the  determination  of  the  bryophytes. 


IV.  PHYSIOGRAPHY 

Cape  Breton  Island  is  about  4,000  square  miles  in  area : it  is 
approximately  four-fifths  as  large  as  the  state  of  Connecticut.  Its 
greatest  length  (from  the  Gut  of  Canso  to  Cape  North)  is  about 
no  miles,  its  greatest  width  (from  Margaree  Harbor  to  Cape 
Breton)  about  75  miles.  The  general  configuration  of  the  island 
is  brought  out  by  the  map  (Fig.  2).  It  comprises  two  distinct 
peninsulas,  which  are  united  at  the  south  by  the  narrow  Isthmus 


264 


George  E.  Nichols, 


of  St.  Peter  (now  cut  by  a ship  canal),  and  which  almost  com- 
pletely enclose  the  Bras  d’Or  Lakes,  an  irregularly  shaped  medi- 
terranean sea  fifty  miles  long  and  in  places  twenty  miles  wide. 
The  area  treated  as  northern  Cape  Breton  in  the  present  paper 
is  about  sixty  miles  long  with  a maximum  width  of  about  thirty 
miles. 

A good  idea  of  the  general  character  of  the  country  is  con- 
veyed by  the  accompanying  series  of  photographs.  In  addition 


Figure  3. — View  of  lowland  and  plateau  from  Middle  Head,  Ingonish: 
in  upper  right  background,  Mt.  Franey;  to  left  of  this,  valley  of  Clyburn 
Brook;  in  foreground,  low  granitic  headland,  drift-covered,  with  second 
growth  forests  of  white  spruce  and  balsam  fir. 

to  those  introduced  in  the  present  connection,  attention  is 
especially  called  to  the  following:  Figs.  21,  24,  26,  28,  30,  33,  38, 
4L  50-  51- 

From  a topographic  standpoint  the  outstanding  feature  of 
northern  Cape  Breton  is  the  great  interior  plateau,  which  stretches 
in  almost  unbroken  continuity  from  Cape  North  nearly  to  the 
Bras  d’Or.  This  massive  remnant  of  the  ancient  Atlantic  L pland 
(Goldthwait  T6),  composed  of  granites,  syenites,  and  other 
highly  resistant,  crystalline  rocks  of  Laurentian  age.  includes  the 
highest  land  in  Nova  Scotia.  The  average  elevation  of  its  sur- 


Vegetation  of  Northern  Cape  Breton. 


265 


face  in  northern  Cape  Breton  is  between  1,000  and  1,200  feet, 
but  in  places  it  is  considerably  higher.2  South  of  the  area  under 
discussion  the  plateau  becomes  greatly  fragmented  and  its  surface 
gradually  approaches  sea  level.  In  southeastern  Cape  Breton  the 
summits  of  the  Laurentian  highlands  rarely  attain  an  elevation 
of  more  than  300  feet. 


Figure  4. — Characteristic  view  on  the  plateau  : looking  westward  from 
an  eminence  north  of  the  Barrasois  River ; primeval  forests  of  balsam 
fir,  etc. 


As  one  approaches  the  eastern  coast  of  northern  Cape  Breton 
in  the  little  coasting  steamer,  which  affords  the  easiest  means  of 
travel  along  the  shore  north  of  Sydney,  the  plateau,  as  viewed 
in  the  distance,  presents  an  even,  unbroken  skyline  (see  especially 
Fig.  30).  But  to  one  standing  on  the  summit  of  Mount  Franey, 
or  some  other  eminence  along  the  eastern  margin  of  the  table- 
land, its  surface  appears  as  a broad  expanse  of  low,  rounded  hills, 
which  stretches  westward  to  the  horizon  (Figs.  4,  51).  Hidden 
away  among  these  distant  hills  are  innumerable  little  lakes  and 
ponds,  countless  deep  valleys  and  wild  gorges. 


2 Mount  Franey  (Fig.  3),  the  loftiest  hill  recorded,  measures  1,370  feet 
in  height.  In  the  opinion  of  the  writer  there  are  numerous  higher  summits 
in  the  interior  of  the  island. 


Trans.  Conn.  Acad.,  Vol.  XXII 


19 


1918 


266 


George  E.  Nichols, 


Figure  5. — View  looking  southward  along  coast  from  near  summit  of 
Mt.  Smoky:  Carboniferous  lowland  in  mid-distance;  elsewhere  the  under- 
lying rocks  are  crystalline. 


Figure  6. — Ingonish  Harbor : Mt.  Smoky  (granitic)  in  distance,  with 
lower  Carboniferous  hills  and  the  shingle  spit  which  partly  encloses  the 
harbor  in  mid-distance ; Carboniferous  lowland  in  foreground. 


Vegetation  of  Northern  Cape  Breton. 


267 


Along  certain  sections  of  the  coast  in  northern  Cape  Breton  the 
crystalline  rocks  extend  bluffly  out  to  the  shore.  In  places,  as 
between  Aspy  Bay  and  Neil’s  Harbor  (Fig.  38),  these  rugged 
granitic  shores  are  relatively  low.  Elsewhere,  as  at  Cape  North 
(Fig.  30)  and  Cape  Smoky  (Fig.  6),  the  mountains  rise  abruptly 
from  the  sea:  at  Cape  Smoky  and  along  the  northwest  shore  are 
magnificent  sea  cliffs  many  hundred  feet  in  height.  But  along 
much  of  the  coast,  a low  border  of  Carboniferous  rocks — sand- 


Figure  7. — The  Big  Intervale  at  Aspy  Bay:  farms  and  second  growth 
forests ; Pyrus  americana  in  right  foreground. 

stone,  shale,  dolomite,  gypsum,  etc. — intervenes  between  the 
crystalline  area  and  the  sea.  On  the  eastern  shore  (Figs. 

5,  26,  33),  and  on  the  western  shore  north  of  Cheticamp, 
this  fringe  of  softer  rocks  is  rarely  more  than  a mile  in 
width ; ordinarily  it  is  much  less.  At  certain  places  even 
here,  however,  as  at  North  River,  Ingonish,  Aspy  Bay 
(Figs.  7,  20),  Bay  St.  Lawrence,  and  Pleasant  Bay,  the 
Carboniferous  lowland  extends  inland  for  several  miles  along 
the  rivers,  forming  broad  intervales.  In  the  southwestern  part  of 
the  area  mapped  (Fig.  2),  in  the  Margaree  district,  the  lowlands 
are  much  more  extensively  developed  than  elsewhere  (Fig.  21). 


268 


George  E.  Nichols, 


It  has  been  inferred  by  some  geologists  that  Cape  Breton 
Island  escaped  glaciation,  and  this  has  been  assumed  as  a 
hypothesis  by  certain  botanists  (Robinson  ’06,  p.  258;  Taylor 
’12,  p.  24),  in  an  attempt  to  explain  certain  peculiarities  of  plant 
distribution.  Such,  however,  is  hardly  the  case.  On  the  plateau, 
to  be  sure,  superficial  deposits  of  any  depth  are  scarce,  the  rock- 
surface  often  being  bare  or  covered  with  granite  boulders  of 
apparently  local  origin.  Soil,  when  present,  is  usually  thin : 


Figure  8. — Mountains  and  granitic,  drift-covered  lowland  north  of 
Cheticamp. 


commonly  it  consists  of  a coarse  quartz  sand  or  gravel  derived 
through  the  decomposition  of  the  underlying  rock.  But  even  on 
the  plateau,  as,  for  example,  along  the  trail  between  Pleasant  Bay 
and  the  Big  Intervale  at'  Aspy  Bay,  there  may  be  found  con- 
siderable deposits  of  drift.  Further,  the  seemingly  complete 
absence  of  a truly  alpine  flora,  even  on  the  higher  summits, 
would  point  strongly  toward  glaciation.  In  the  lowland,  the  Car- 
boniferous formations  everywhere  are  hidden  by  a mantle  of 
glacial  debris : in  places  along  the  coast,  as  at  French  River  and 


Vegetation  of  Northern  Cape  Breton.  269 

Pleasant  Bay,  there  are  sea  bluffs,  more  than  fifty  feet  high,  com- 
posed entirely  of  glacial  drift,  while  in  some  of  the  brook  valleys, 
e.  g.,  in  that  of  Power  Brook,  there  are  accumulations  of  drift 
fully  as  deep.  Glacial  striae  have  been  observed  in  several 
localities  (Fletcher  ’85,  p.  77H),  but,  owing  to  the  rapidity  with 
which  most  of  the  rocks  crumble  when  exposed  to  the  weather, 
such  evidences  of  glaciation  are  rare. 

The  distribution  of  roads  and  settlements  in  northern  Cape 
Breton  has  been  determined  largely  by  the  character  of  the 
topography  and  of  the  soil.  Along  the  east  coast  a road  follows 
the  shore  from  St.  Ann’s  Bay  to  Cape  North,  with  branches 
extending  inland  a short  distance  wherever  intervales  occur. 
From  the  head  of  the  Big  Intervale  at  Aspy  Bay  (Fig.  7),  a 
rough  trail  crosses  the  plateau  to  Pleasant  Bay,  and  leads  thence 
southward  over  the  mountains  toward  the  mouth  of  the  Cheti- 
camp  River,  where,  in  conformity  with  the  better  character  of 
the  country,  roads  are  again  encountered.  The  southwestern 
part  of  the  area  mapped  affords  excellent  farming  and  is  well 
populated,  but  elsewhere  the  farms,  for  the  most  part,  are  con- 
fined to  the  intervales  and  to  the  low  coastal  strip.  The  agricul- 
tural possibilities  of  many  of  the  tracts  which  have  been  brought 
under  cultivation  would  scarcely  have  been  appreciated  by  any 
save  the  Scotch  Highlanders,  whose  descendants  constitute  the 
larger  proportion  of  the  population  of  the  country.  At  several 
points  along  the  coast,  as  at  Cheticamp  and  Neil’s  Harbor, 
the  fishing  industry  supports  considerable  communities.  The 
mountainous  interior  of  northern  Cape  Breton  is  a wilderness, 
uninhabited  and  roadless,  difficult  to  travel  and  little  known, 
seldom  visited  except  by  trappers  and  hunters. 

V.  CLIMATE 

In  Table  I are  given  the  average  temperature  and  precipita- 
tion records  for  twenty  years  at  Sidney.3  Although  there  are 
known  to  be  certain  discrepancies,  in  a general  way  these  figures 
doubtless  represent  the  meteorological  conditions  in  northern  Cape 
Breton.  For  purposes  of  comparison,  climatic  data  for  various 


3 Part  of  the  climatic  data  here  given  has  been  supplied  by  Director  R.  F. 
Stupart  of  the  Canadian  Meteorological  Service.  The  remainder  has  been 
secured  from  various  sources. 


270 


George  E.  Nichols, 


selected  stations  in  eastern  Canada  are  briefly  presented  in 
Table  II.  Of  the  stations  here  listed,  the  first  five  are  in  the 
Maritime  Provinces:  Sidney,  Halifax,  and  Yarmouth  front  on 
the  ocean,  and  St.  John  on  the  Bay  of  Fundy;  while  Frederickton 

TABLE  I 

Average  Temperature  and  Precipitation  Records  for  Twenty  Years 

at  Sydney,  N.  S. 


Month 

Degrees  of  Temperature,  Fahrenheit 

Precipitation 

1 Number 

Tota! 

Amount  . - 

(Inches)1  Cc°‘ 

or  more  > 

Mean 

Daily 

Mean 

Daily 

Maximum 

Mean 

Daily 

Minimum 

Monthly 

Maximum 

Extremes 

Minimum 

January . . . 

23 

31 

15 

57 

-14 

5.19  12 

February . . 

21 

30 

13 

59 

—15 

4-39  10 

March  .... 

28 

36 

20 

58 

-18 

! 4-90  13 

April 

37 

44 

29 

77 

3 

4.O4  12 

May 

46 

55 

37 

78 

22 

3.00  II 

) une 

55 

64 

45 

86 

28 

2.66  10 

July 

64 

73 

54 

92 

35 

3.16  10 

August  . . . 

63 

72 

54 

88 

36 

3-03  11 

September. 

57 

66 

48 

88 

30 

3.4S  11 

October  . . . 

48 

56 

40 

77 

25 

4. 11  13 

November. 

39 

45 

34 

67 

12 

5-63  14 

December . 

30 

36 

24 

58 

O 

5.92  14 

Year 

42 

51 

33 

92 

-18 

49-51  11 

TABLE  II 

Temperature  and  Precipitation  Data  for  Various  Stations 
in  Eastern  Canada 


Station 

Temperature  (in  Degrees  Fahrenheit) 

Precipitation 

Normal 
Mean  Daily 
for 

Hottest 

Month 

Normal 
Mean  Daily 
for 

Coldest 

Month 

Average 
Extreme 
Maximum 
for  Y ears 
1907-1914 

Average 
Extreme 
Minimum 
for  Years 
1907-1914 

Per  cent. 
Normal  , Falling 
Annual  1 in 

Amount  Months 
• (inches)  October- 
March 

Sydnej',  N.  S 

64 

211 

ss 

— TO 

49.51  61 

Halifax,  N.  S 

65 

24 

91 

— IO 

56.S1  57 

Yarmouth,  N.  S.  . . . 

6l 

27 

78 

I 

51-94  55 

St.  John.  N.  B 

6l 

19 

So 

-13 

4S.0S  55 

Frederickton,  N.  B. 

66 

13 

92 

-27 

46.44  56 

Quebec,  Oue 

66 

IO 

90 

—24 

; 41-10  4Q 

Montreal,  Oue 

69 

13 

91 

-is 

40.32  52 

Port  Arthur,  Ont.  . . 

62 

7 

91 

-32 

23.22  29 

Vegetation  of  Northern  Cape  Breton. 


271 


lies  inland,  about  fifty  miles  west  of  St.  John.  Of  the  three 
remaining  stations,  Quebec  and  Montreal  are  situated  in  southern 
Quebec,  about  200  miles  from  the  seacoast,  and  Port  Arthur  is 
located  in  western  Ontario,  on  the  north  shore  of  Lake  Superior. 
This  latter  station  is  introduced,  partly  because  it  exemplifies  the 
relatively  continental  as  compared  with  the  relatively  maritime 
type  of  climate,  and  partly  because  of  its  proximity  to  Isle  Royale, 
the  scene  of  Cooper’s  investigations  (’13). 

Northern  Cape  Breton  may  be  said  to  possess  a cool-temper- 
ate, maritime  climate.  In  the  following  paragraphs  the  general 
climatic  features  of  this  region  are  briefly  summarized,  and  atten- 
tion is  called  to  certain  differences  between  the  climate  of  the 
plateau  and  that  of  the  lowland. 

a.  GENERAL  CLIMATIC  FEATURES  OF  NORTHERN  CAPE  BRETON 

T emperature. — As  compared  with  regions  which  are  not  in 
close  proximity  to  the  ocean,  the  temperature  here  is  more  equable. 
Some  idea  of  the  difference  is  suggested  by  the  figures  in  Table  II. 
It  will  be  seen  here,  for  example,  that  the  disparity  between  the 
mean  temperatures  for  the  warmest  and  coldest  months  of  the 
year  at  Sydney  is  only  43 °,  as  compared  with  53 0 at  Frederickton, 
and  550  or  more  at  Quebec,  Montreal,  and  Port  Arthur.  This 
same  dissimilarity  between  coastal  and  interior  regions  is  brought 
out  by  comparing  the  extreme  maximum  and  minimum  tempera- 
tures for  the  year  at  the  various  stations.  The  winters  in  north- 
ern Cape  Breton  are  long  and  cold,  but  extremes  of  temperature 
such  as  prevail  toward  the  interior  of  the  continent  are  seldom 
experienced  (see  Table  II).  Spring  is  sometimes  very  late  in 
arriving,  owing  partly  to  the  quantity  of  drift  ice  in  the  adjacent 
waters.  The  summers  are  short  and  cool,  but  there  are  only 
three  months  in  the  year  when  the  mean  monthly  minimum  at 
Sydney  is  lower  than  320.  This  latter  fact  is  in  marked  contrast 
to  the  conditions  at  Port  Arthur  (see  Cooper  ’13,  p.  8),  where 
the  mean  monthly  minimum  is  higher  than  320  only  during  June, 
July,  and  August. 

Precipitation. — In  common  with  other  regions  along  the 
Atlantic  Coast  the  precipitation  in  northern  Cape  Breton  is 
copious  and  is  well  distributed  over  the  entire  year.  More  than 
60  per  cent,  of  it  comes  during  the  period  of  comparative  vegeta- 
tive inactivity,  a condition  quite  the  reverse  of  what  prevails  in 


272 


George  E.  Nichols, 


the  interior  of  the  continent  (see  Table  II),  and  also  to  that 
which  characterizes  the  Atlantic  Coast  farther  south  (at  Charles- 
ton, S.  C.,  for  example,  out  of  an  annual  precipitation  of  52.07 
inches,  only  39  per  cent,  falls  during  the  period  from  October  to 
March).  Snowfall  in  winter  is  usually  heavy  and,  on  account  of 
the  backward  spring,  the  snow  commonly  remains  on  the  ground 
for  a long  time.  Fletcher  (’85,  p.  86)  notes  that  in  the  middle 
of  June,  1881,  patches  of  snow  still  lingered  in  sheltered  situa- 
tions, while  in  1914  and  1915  the  writer  observed  snow-ice  as 
late  as  August  at  the  foot  of  an  open  north-facing  slope  along  the 
Barrasois  River. 

H Timidity. — Fogs  are  more  or  less  prevalent  at  all  seasons,  and 
even  in  clear  summer  weather  the  humidity  of  the  atmosphere  is 
quite  perceptible.  Figures  regarding  the  rate  of  evaporation 
throughout  the  growing  season  are  not  available,  but  during  the 
summer  of  1915,  for  a period  of  nearly  three  weeks,  the  writer 
operated  a series  of  porous  cup  atmometers  in  various  habitats, 
and  the  results  obtained  from  those  set  up  in  the  open  near  the 
coast  are  given  in  Ta.ble  III.  The  readings  in  the  first  four 
columns  of  this  table  were  taken  near  the  Barrasois  River.  The 
“Shore”  station  was  situated  on  an  exposed,  east-facing  hillside. 

TABLE  III 

Rate  of  Evaporation  Along  the  Coast  of  Northern  Cape  Breton 
During  the  Summer  of  1915,  as  indicated  by  the 
Porous  Cup  Atmometer 


Station 

July  22-July 
27 

July  27- 
August  3 

August  3- 
August  7 

Daily 

Average 

August  20- 
August  23 

Shore 

28.8  cc. 

45  CC. 
53-3  cc. 

S4.2  CC. 
91.9  cc. 

9.8  CC. 
II. 5 CC. 

j 79.2  CC. 
(sK  days) 

Intervale 

39-4  cc. 

about  a quarter  of  a mile  from  the  seacoast.  The  “Intervale” 
station  was  located  in  a similar  site  about  five  miles  from  the 
shore,  at  the  head  of  a broad  open  valley.  The  figures  in  the 
fifth  column  were  obtained  from  an 'instrument  set  up  on  a low 
hill  at  Ingonish,  within  a stone’s  throw  of  the  open  ocean.  The 
average  daily  rate  of  evaporation  for  the  entire  period  at  the  shore 
stations  was  about  12.2  cc.  During  the  period  of  July  22— 
August  3 there  was  considerable  rain  and  fog.  while  during  the 


Vegetation  of  Northern  Cape  Breton. 


273 


periods  August  3-7,  20-23,  the  weather  was  uniformly  clear. 
For  these  latter  periods  the  daily  rate  of  evaporation  at  the  shore 
stations  averaged  21.7  cc.  The  evaporation  rate  at  the  intervale 
station,  it  will  he  noted,  averaged  slightly  higher  than  that  at  the 
shore  station. 

b.  CLIMATE  OF  THE  INTERIOR  PLATEAU  COMPARED  WITH  THAT 

OF  THE  COAST 

Temperature. — Aside  from  a few  figures  obtained  by  the 
writer,  few  accurate  comparative  data  are  available  regarding 
climatic  conditions  on  the  plateau,  although  various  interesting 
observations  have  been  supplied  by  trappers.  In  August,  1915, 
two  recording  thermometers  were  set  up  in  the  open,  one  near 
the  shore  at  Ingonish,  the  other  in  the  barrens  about  fifteen  miles 
west  of  Ingonish  (elevation  perhaps  1,200  feet).  During  the 
writer’s  stay  in  the  barrens  daily  readings  were  made  from  these 
instruments,  and  subsequently  readings  were  taken  at  intervals 
of  a few  days  by  a competent  guide,  who  made  trips  into  the 
barrens  for  this  purpose.  The  readings  were  continued  at  each 
station  until  a temperature  of  32 0 or  lower  had  been  recorded. 

The  figures  given  in  Table  IV  and  covering  part  of  this  period 

* 

TABLE  IV 


Maximum  and  Minimum  Temperatures  (°F.)  in  the  Interior  and  Along 
the  Coast  of  Northern  Cape  Breton;  August  18-23,  1915 


Mean  Daily 

Mean  Daily 

Mean  Daily 

Extreme 

Extreme 

Maximum 

Minimum 

Range 

Maximum 

Minimum 

Barrens 74° 

43° 

26° 

8o° 

43° 

Ingonish 710 

56° 

15° 

75° 

52° 

are  suggestive,  if  nothing  more.  It  is  of  interest  to  note  that 
the  daily  maximum  temperature  in  summer  is  frequently  higher, 
and  the  daily  minimum  invariably  lower,  while  the  average 
daily  range  of  temperature  is  perceptibly  greater  on  the  plateau 
than  along  the  coast.  Observations  recorded  for  nine  days 
show  the  average  daily  minimum  to  range  from  six  to  ten 
degrees  lower  on  the  plateau  than  along  the  coast,  and  the 
average  daily  maximum  about  one  degree  lower.  For  the  bar- 
rens station  the  first  freezing  temperature  was  recorded  on. 


274 


George  E.  Nichols, 


September  8 (30°),  eighteen  days  earlier  than  at  the  Ingonish 
station  (September  26:  31  °).  There  is  little  doubt  that  on  the 
plateau,  during  some  seasons,  the  temperature  falls  below  freez- 
ing during  every  month  of  the  year.  And  not  only  are  the  daily 
minimum  temperatures  here  during  the  growing  season  lower 
than  in  the  lowland,  but  the  growing  season  is  considerably 
(probably  from  six  weeks  to  two  months)  shorter  here  than 
there. 

Precipitation,  Evaporation  and  Wind. — No  exact  observations 
have  been  made  regarding  precipitation  on  the  plateau,  but 
from  the  writer’s  experience  and  from  numerous  inquiries  it 
can  be  stated  with  certainty  that  during  summer  the  rainfall  is 
somewhat  heavier  here  than  along  the  coast.  The  evaporating 
power  of  the  air  in  clear  weather,  at  least  during  the  summer,  is 
apparently  greater  than  along  the  coast.  This  observation  is 
deduced  from  atmometer  readings,  taken  for  the  brief  period 
of  three  and  a half  clear  days  in  August,  when  an  instrument  on 
the  barrens  indicated  a daily  evaporation  rate  of  28.4  cc.,  as 
compared  with  22.6  cc.  near  the  shore  at  Ingonish.  But,  on  the 
whole,  the  humidity  of  the  atmosphere  is  greater  on  the  plateau 
than  on  the  lowland.  This  is  due  to  the  prevalence  here  of 
fog's.  During  dull  weather  the  “clouds  hang  low,  covering  the 
slopes  and  summits  of  the  mountains  above  an  elevation  of  seven 
or  eight  hundred  feet,  sometimes  for  days  at  a time.  Even 
though  it  may  not  actually  rain,  everything  is  saturated  with 
moisture.  The  higher  rate  of  evaporation  during  clear  weather 
is  correlated  with  the  heavy  winds  which  sweep  across  the 
plateau  at  all  seasons.  So  effective  are  these  that  a wet,  spongy 
hed  of  cladonias  may  become  dry  and  brittle  within  a few  hours. 
The  effect  of  wind  on  the  vegetation,  as  seen  in  the  barrens, 
is  even  more  pronounced  in  winter  than  during  the  growing 
season.  This  will  be  discussed  later  in  connection  with  the  vege- 
tation of  the  barrens. 

VI.  ECOLOGICAL  CLASSIFICATION  OF  MATERIAL; 

NOMENCLATURE 

The  ecological  classification  adopted  in  the  present  paper  has 
already  been  described  in  considerable  detail  elsewhere  (Nichols 
’17),  and  need  be  only  briefly  outlined  here.  The  fundamental 
unit  of  vegetation  from  the  standpoint  of  physiographic  ecology 


Vegetation  of  Northern  Cape  Breton. 


275 


is  the  plant  association:  any  group  or  community  of  plants, 
taken  in  its  entirety,  which  occupies  a common  habitat.  Asso- 
ciations which  are  correlated  with  a common  type  of  habitat 
and  which  are  ecologically  equivalent  to  one  another  may  be 
referred  to  a common  association-type.  The  culminating  mem- 
ber of  any  specific  successional  series  is  termed  an  cdaphic 
climax  association.  In  favorable  situations  this  edaphic  climax 
coincides  with  the  regional  climax  association-type : the  most 
mesophytic  type  of  vegetation  of  which  the  climate  of  the 
region  permits  the  development  on  ordinary  uplands.  But,  in 
unfavorable  situations,  the  edaphic  climax  may  be  represented 
by  an  association  which  is  less  mesophytic  than  the  regional 
climax  type. 

Parenthetically,  it  may  be  remarked  that  while  emphasis  is 
usually  placed,  as  above,  on  the  relatively  high  degree  of  meso- 
phytism  which  characterizes  the  regional  climax  association-type, 
it  is  quite  likely  that  this  conception,  while  in  general  doubtless 
holding  true,  should  be  altered  somewhat.  In  the  lowland  of 
northern  Cape  Breton,  for  example,  a coniferous  forest  associa- 
tion on  ordinary  uplands  represents  either  a temporary-  stage, 
destined  to  give  way  to  deciduous  forest,  or  else  an  edaphic 
climax  (see  definition  below)  ; yet  not  infrequently,  in  so  far 
as  their  relative  mesophvtism  is  concerned,  such  forests  seem 
quite  on  a par  with  forests  of  the  regional  climax  type.  The 
differentiating-  factors  concerned  in  this  particular  case  are  sug- 
gested in  the  writer’s  discussion  of  the  ecological  relations  of  the 
balsam  fir  (p.  285). 

In  any  unit  area  where  more  than  one  association  is  repre- 
sented, the  associations,  taken  collectively,  constitute  an  associa- 
tion-complex. Within  any  specific  geographic  region  the 
associations  are  grouped  naturally  into  a series  of  more  or  less 
definite  complexes  with  reference  to  the  physiographic  features 
of  the  region,  i.  e.,  with  reference  to  topography  and  soil.  Any 
association-complex  which  is  thus  related  to  a specific  physio- 
graphic unit  area  constitutes  an  edaphic  formation.  Edaphic 
formations  which  are  correlated  with  a common  type  of 
physiographic  unit  area  may  be  referred  to  a common  cdaphic 
formation-type.  The  edaphic  formations  of  any-  unit  area, 
where  more  than  one  is  present,  taken  collectively,  constitute 
an  cdaphic  formation-complex.  The  edaphic  formation-complex 


276 


George  E.  Nichols, 


of  any  climatic  region  constitutes  a climatic  formation.  To  sum 
up : the  association  is  a unit  determined  by  habitat ; the  edaphic 
formation  is  a unit  determined  by  physiography — a unit  of  a 
higher  order  than  the  association;  while  the  climatic  formation 
similarly  is  a unit  determined  by  climate — a unit  of  a still  higher 
rank  than  either  of  the  preceding. 

In  the  account  of  the  ecological  relations  of  the  vegetation  of 
northern  Cape  Breton  which  follows,  the  two  climatic  forma- 
tions here  represented  are  discussed  separately.  The  scheme 
followed  in  classifying  the  innumerable  associations  which,  taken 
collectively,  comprise  the  vegetation  of  the  respective  regions 
concerned  is  partially  outlined  in  the  table  of  contents,  which 
may  be  looked  upon  as  in  the  nature  of  an  analytical  key.  For 
the  benefit  of  readers  to  whom  the  writer’s  paper  on  classifica- 
tion may  not  be  available,  a few  further  remarks  regarding  the 
system  on  which  this  synopsis  is  built  up  may  be  added. 

First  of  all,  taking  into  account  their  successful  relations  to 
one  another  and  their  distribution  with  reference  to  specific 
physiographic  unit  areas,  the  various  individual  units  of  vegeta- 
tion, the  associations,  have  been  assembled  into  definite  associa- 
tion-complexes. An  individual  association-complex,  as  thus 
defined,  constitutes  an  edaphic  formation.  For  obvious  reasons, 
however,  the  various  individual  associations  have  been  treated 
collectively,  as  association-types,  and,  similarly,  emphasis  has 
been  laid  on  the  edaphic  formation-types  rather  than  on  the 
individual  formations  (see  definitions  above).  Proceeding  fur- 
ther, the  edaphic  formations  (and  formation-types)  of  the  region 
have  been  divided  primarily  with  reference  to  the  water  rela- 
tions of  the  areas  which  they  occupy  into  two  successional 
series : formations  of  the  xerarch  series,  and  formations  of  the 
hydrarch  series.4  Under  each  of  these  two  heads,  in  the  case 
of  the  region  of  deciduous  forests,  it  has  seemed  desirable  to 
distinguish  between  primary  and  secondary  formations,  the  latter 
embracing  formations  in  which  the  vegetation  has  been  modified 

4 The  term  xerarch,  to  quote  Cooper  (’13,  p.  11),  “is  applied  to  those 
successions  which,  having  their  origin  in  xerophytic  habitats,  such  as  rock 
shores,  beaches,  and  cliffs,  become  more  and  more  mesophytic  in  their 
successive  stages ; . . . [the  term  hydrarch]  to  those  which,  originating 
in  hydrophytic  habitats,  such  as  lakes  and  ponds,  also  progress  toward 
jmesophytism.” 


Vegetation  of  Northern  Cape  Breton.  277 

by  cultivation,  lumbering,  or  tire.  The  formations  of  the 
xerarch  and  hydrarch  series  respectively  are  further  subdivided 
with  reference  to  the  general  topographic  features  of  the  region, 
these  being  considered  from  the  standpoint  of  their  relationship 
to  one  another  through  physiographic  development.  Thus, 
among  the  formations  of  the  xerarch  series,  three  groups  of 
formation-types  are  distinguished : the  formation-types,  respec- 
tively, of  ordinary  uplands,  of  uplands  along  streams,  and  of 
uplands  along  the  seacoast.  In  the  same  way,  the  formation- 
types  of  the  hydrarch  series  fall  more  or  less  naturally  into  three 
groups : the  formation-types  of  lakes,  ponds  and  swamps  inland, 
the  formation-types  in  and  along  rivers  and  streams,  and  the 
formation-types  along  the  seacoast.  The  classification  of  forma- 
tion-types primarily  on  the  basis  of  water  supply  is  open  to  cer- 
tain objections,  but  so  also  is  their  classification  primarily  on  the 
basis  of  physiography,  a method  which  might  perhaps  equally 
well  have  been  followed. 

In  discussing  the  vegetation  of  each  region,  the  regional 
climax  association-type  is  taken  up  first,  since  an  understanding 
of  this,  representing  as  it  does  the  highest  degree  of  mesophytism 
permitted  by  the  climate — the  climatic  indicator,  so  to  speak,  is 
prerequisite  to  an  adequate  interpretation  of  subordinate  asso- 
ciation-types and  of  successional  relations.  The  edaphic  forma- 
tion-complex of  the  region,  which  of  course  includes  all  the 
edaphic  formations  and  formation-types,  with  the  associations 
and  association-types  which  comprise  them,  including  the 
regional  climax  association-type,  is  then  considered,  after  the 
manner  outlined  in  the  preceding  paragraph. 

In  matters  of  nomenclature  the  author,  in  general,  has  fol- 
lowed the  seventh  edition  of  Gray’s  Manual  (’08),  with  the 
emendations  of  Robinson  and  Fernald  (’09),  for  the  vascular 
plants,  his  own  papers  on  the  bryophytes  of  Cape  Breton  (T6a. 
T8)  for  the  mosses  and  liverworts,  and  Fink’s  Lichens  of 
Minnesota  (To)  for  the  lichens.  In  the  case  of  the  vascular 
plants,  changes  in  nomenclature  since  the  publication  of  the 
Manual  for  the  most  part  have  been  neglected.  Only  in  excep- 
tional cases  are  authorities  cited  for  the  names  used.  In 
cases  where  a plant  is  referred  to  by  its  common  name,  the 
scientific  name  is  usually  given  only  in  connection  with  its  first 
mention  in  the  text. 


THE  DECIDUOUS  FOREST  CLIMATIC  FORMATION  IN 
NORTHERN  CAPE  BRETON 

I.  THE  REGIONAL  CLIMAX  ASSOCIATION-TYPE:  THE 
CLIMAX  FOREST 

Present  and  past  distribution  of  the  climax  forest. — To  one 
visiting  northern  Cape  Breton  at  the  present  day  the  prevailing 
aspect  of  the  lowland  forests  (Figs.  9,  39,  42,  etc.)  appears  to 


Figure  9. — Second  growth  woodlands  of  balsam  fir  and  white  spruce : 
Barrasois. 


be  coniferous : white  spruce  and  balsam  fir  predominate  on 
every  side.  But  practically  all  of  these  forests  are  secondary  in 
their  origin.  Although  settlements  in  this  region  for  the  most 
part  date  back  scarcely  one  hundred  years,  during  this  short 
period  the  greater  part  of  the  country  has  been  either  cut  or 
burned  over,  and  much  of  it,  at  one  time  or  another,  has  been 
cultivated  or  used  for  pasturage.  In  view  of  the  widespread 
destruction  or  modification  of  the  original  vegetation,  the  nature 
of  the  primeval  forests  must  be  judged  very  largely  from  the 


George  E.  Nichols,  Vegetation  of  Northern  Cape  Breton.  279 

scattered  vestiges  which  for  one  reason  or  another  have  remained 
intact.  From  the  study  of  many  such  fragments,  together  with 
certain  little  modified  tracts  of  second  growth  forest,  it  has 
become  unmistakably  evident  that  in  former  times  a very  large 


Figure  10. — Primeval  forest  of  the  regional  climax  type,  on  lower 
slopes  of  mountains  along  Northeast  Margaree  River;  mostly  beech  and 
maple ; balsam  fir  well  represented  in  undergrowth  and  to  some  extent  in 
mature  stand. 

portion  of  this  area  was  clothed  with  forests  in  which  the  pre- 
dominant trees  were  deciduous.  It  is  certain  (and  this  conclu- 
sion is  confirmed  by  statements  of  many  of  the  older  settlers) 
that  forests  of  this  sort  were  developed  in  practically  all  edaphi- 
cally  favorable  situations ; they  were  by  no  means  local  in  their 
occurrence,  but  rather  of  very  general  distribution.  The 


280 


George  E.  Nichols, 


structure  of  these  regional  climax  forests  is  considered  in  brief 
detail  in  the  following  paragraphs.  Their  general  aspect  is 
illustrated  by  Figs.  10-12. 

The  trees  of  the  climax  forest. — The  nature  of  the  individual 
associations  which  comprise  the  climax  association-complex  of 
the  lowland  varies  considerably.  In  some  places  the  forest  is 
made  up  wholly  of  deciduous  trees,  but  more  commonly  it  con- 
sists of  a mixture  of  deciduous  and  evergreen  species.  The 
various  trees  which  may  enter  into  the  composition  of  the  forest 
are  named  below,  together  with  remarks  as  to  their  frequency 
and  ecological  importance.  ( 1 ) Deciduous  Species  : — Beech 
(Fagus  grandi folia)  is  almost  invariably  the  predominant  species, 
in  some  cases  including  fully  65  per  cent,  of  the  mature  trees. 
Sugar  Maple  ( Acer  saccharum ) is  always  present  and  usually 
ranks  second  in  abundance  to  the  beech.  Yellow  Birch  {Betid a 
lutea)  is  likewise  omnipresent  and  sometimes  outnumbers  the 
sugar  maple.  Red  Maple  ( Acer  mb  rum ) is  rarely  absent,  and 
frequently  occupies  a prominent  position  in  the  forest.  Paper 
Birch  ( Be  tula  alba  papyrifcra ) ordinarily  grows  scattered 
through  the  forest.  In  some  stands  these  five  species  are  the 
only  large-sized  trees  represented  in  the  mature  growth.  The 
northern  Red  Oak  ( Q it  ere  us  rubra  ambigua ) is  widely  distributed, 
and  in  some  localities,  as  at  Pleasant  Bay  and  in  the  vicinity 
of  Cape  North,  is  an  important  constituent;  but  in  most  places 
it  is  only  sparingly  represented,  and  often  it  is  absent.  White 
Ash  ( Fraxinus  americana ) is  not  uncommon  in  many  low  inter- 
vale forests,  but  elsewhere  it  is  comparatively  rare.  Balsam 
Poplar  (Populus  balsamifera ) is . occasionally  encountered  in 
virgin  forests.  (2)  Evergreen  Species  (conifers)  : — Balsam  hr 
( Abies  balsamea ),  in  the  majority  of  cases,  is  a conspicuous, 
though  not  necessarily  abundant,  member  of  the  forest,  growing 
intermixed  with  the  various  deciduous  species.  Hemlock  ( Tsuga 
canadensis ) is  locally  abundant  and  sometimes  is  the  pre- 
dominant tree ; but  often  it  is  absent  or  represented  only  by 
scattered  trees.  White  Pine  ( Finns  Strobus ) is  also  an  important 
constituent,  locally,  at  any  rate.  It  is  particularly  characteristic 
of  the  steep,  well-drained,  rocky  slopes  and  ridges  which  flank 
many  of  the  larger  streams ; but  repeated  cutting  has  thinned 
out  this  tree  to  a greater  extent  than  any  other  single  species. 
White  Spruce  ( Picea  canadensis ) grows  sprinkled  here  and  there 


Vegetation  of  Northern  Cape  Breton. 


281 


through  the  forest,  though  seldom  present  in  quantity.  Black 
Spruce  (Picea  mariana ) also  is  frequently  represented  by 
scattered  specimens. 

In  the  account  which  follows,  for  the  sake  of  convenience, 
forests  of  the  usual  climax  type,  predominantly  deciduous  but 
with  a more  or  less  pronounced  admixture  of  evergreen  trees, 
are  frequently  referred  to  simply  as  “deciduous  forests.” 


Figure  ii. — Primeval  forest  of  the  regional  climax  type,  along  Indian 
Brook;  mostly  beech,  maple,  and  hemlock,  with  some  yellow  birch  and 
balsam  fir ; dense  undergrowth  of  yew. 

Size  of  trees  in  climax  forest. — • The  relatively  large  size 
attained  by  some  of  the  trees  in  the  primeval  forests  of  northern 
Cape  Breton  is  suggested  by  the  following  diameter  measure- 
ments5 which  were  noted  for  various  species : beech,  25  inches ; 
sugar  maple,  36  inches;  yellow  birch,  42  inches;  red  maple,  18 
inches ; paper  birch,  about  3 feet ; red  oak,  35  inches ; white 
ash,  24  inches;  balsam  poplar,  about  2 feet;  balsam  fir,  16  inches; 
hemlock,  30  inches ; white  pine,  about  30  inches ; white  spruce, 
26  inches;  black  spruce,  about  12  inches. 


6 Diameter  measurements  of  trees  were  taken  at  breast  height. 


282 


George  E.  Nichols, 


Woody  undergrowth  in  the  climax  forest. — Two  small  trees, 
the  mountain  maple  ( Acer  spicatum ) and  the  moosewood  ( Acer 
pennsylvanicum) , are  usually  conspicuous  in  the  undergrowth. 
The  latter  species  sometimes  attains  a diameter  of  nearly  a foot, 
but.  in  the  forest,  both  are  usually  little  more  than  shrubs.  The 
mountain  ash  ( Pyrus  americana ) is  not  infrequent,  but  is  more 
characteristic  of  the  evergreen  coniferous  climax  forest  of  the 


Figure  12. — Primeval  forest  of  the  regional  climax  type,  at  Tarbet,  along 
the  Barrasois;  mostly  beech,  maple,  and  yellow  birch;  balsam  fir 
abundant  in  undergrowth  but  absent  from  mature  stand. 

highland.  Of  the  shrubs,  the  yew  ( Taxus  canadensis ) is  the 
most  characteristic  species : usually  this  is  common,  and  fre- 
quently it  forms  a dense  tangle  which  excludes  other  plants  in 
much  the  same  way  that  the  mountain  laurel  ( Kalmia  latifolia  ) 
does  in  the  woods  of  southern  New  England.  Sometimes,  how- 
ever, the  yew  is  entirely  absent  over  considerable  areas.  The 
northern  hazel-nut  ( Corylus  rostrata ) occupies  a position  in  the 
forest  here  somewhat  parallel  to  that  held  by  the  witch  hazel 
in  woods  farther  south.  A few  other  shrubs  are  ordinarily 
represented  by  scattered  specimens,  namely : fly  honeysuckle 


Vegetation  of  Northern  Cape  Breton. 


283 


( Lonicera  canadensis) , withe-rod  ( Viburnum  cassinoides) , 
gooseberry  ( Ribes  lacustre),  dogberry  ( Cornus  alternifolia) , 
and  red-berried  elder  ( Sambucus  racemosa) . The  hobble  bush 
( Viburnum  alnifolium),  one  of  the  most  representative  shrubs 
of  the  climax  forest  throughout  much  of  the  transition  region, 
is  very  local  in  northern  Cape  Breton. 

The  herbaceous  vascular  plants  of  the  climax  forest. — The 
following  list  includes  the  more  characteristic  ferns  and  her- 
baceous seed  plants  of  the  regional  climax  forest.6 


Phegopteris  polypodioides  cc 

Polystichum  acrostichoides  fc 

Polystichum  Braunii  If 

Aspidium  noveboracense  fc 

Aspidium  Filix-mas  Ic 

Aspidium  marginale  Ic 

Aspidium  spinulosum  var.  cc 

Botrychium  virginianum  of 

Lycopodium  lucidulum  cc 

Carex  arctata  fo 

Clintonia  borealis  cc 

Smilacina  racemosa  ff 

Maianthemum  canadcnsc  cc 

Streptopus  roseus  cc 

Medeola  virginiana  ff 

T rillium  cernuum  of 

Habenaria  orbiculata  co 

Epipactis  decipiens  co 


Epipactis  tesselata  co 

Coralorrhiza  maculata  co 

Actaea  rubra  cf 

Actaea  alba  Ir 

Oxalis  Acetosella  cf 

Viola  canadensis  of 

Viola  incognita  cf 

Aralia  nudicaulis  cc 

Sanicula  marilandica  of 

Pyrola  elliptica  cf 

Monotropa  uniflora  cf 

Monotropa  Hypopitys  fo 

Trientalis  antericana  cc 

Epifagus  virginiana  If 

Mitchella  repens  cf 

Linnaea  borealis  americana  of 
Aster  acuminatus  cc 


Several  species  have  been  omitted  from  this  list  which  are 
characteristic  of  low-lying  intervale  forests,  but  not  of  climax 
forests  in  general.  These  will  be  noted  later. 


6 In  this  and  in  several  subsequent  lists  of  the  plants  characteristic  of 
the  climax  association-type,  an  attempt  has  been  made  to  indicate  both 
their  general  prevalence  and  their  relative  abundance  when  present.  The 
following  symbols  are  used  : c = common;  f = frequent;  o — occasional ; 
r=  rare;  l = local.  In  each  case  two  symbols  are  given,  the  first  indicat- 
ing merely  the  frequentness  with  which  the  species  is  represented  (i.  e., 
is  either  present  or  absent)  in  associations  of  the  climax  type,  the  second 
indicating  its  relative  abundance,  when  present,  in  the  individual  associa- 
tion. For  various  reasons  it  has  not  seemed  feasible  to  carry  out  this 
scheme  in  connection  with  other  association-types. 


284 


George  E.  Nichols, 


The  bryophytes  and  lichens  of  the  climax  forest. — Corticolous 
mosses  and  liverworts  form  a striking  feature  of  these  forests. 
Loose  mats  of  Neckera  and  Leucodon,  Porella  and  Frullania 
often  literally  plaster  the  trunks  of  maple  and  other  trees ; Ulota 
grows  in  scattered,  compact  tufts,  particularly  on  trunks  of 
beech;  while  two  lichens,  Sticta  pulmonaria  and  Parmelia  saxa- 
tilis,  are  of  very  common  occurrence.  Tree  bases,  logs  and  rocks 
also  are  usually  hidden  by  masses  of  Bazzania,  Anomodon  and 
various  Hypnaceae.  A list  of  some  of  the  more  conspicuous 
species  follows : 

Bazzania  trilobata  cc 

Ptilidium  ciliare  cf 

Porella  platyphylloidea  cc 

Frullania  Tamarisci  cc 

Dicranum  longifolium  ff 

Dicranum  scoparium  cc 

Ulota  ulophylla  cc 

Mnium  cuspidatum  cc 

Leucodon  sciuroides  cf 

Neckera  pennata  cc 

Heterocladium  squarrosulum  cf 
Anomodon  attenuatus  ff 

Leskeella  nervosa  co 

But  while  mosses  and  liverworts  are  present  in  profusion  in 
these  deciduous  climax  forests,  it  is  important  to  note  that  they 
develop  luxuriantly  for  the  most  part  only  on  substrata  which 
are  elevated  above  the  general  level  of  the  forest  floor.  On  the 
forest  floor  itself  the  bryophytes  usually  are  sparsely  represented 
and  they  may  be  totally  absent  over  considerable  areas.  This 
is  in  striking  contrast  to  the  conditions  which  prevail  in  the 
evergreen  coniferous  climax  forests  of  the  highland,  where  the 
ground  is  almost  always  carpeted  by  a rich  growth  of  bryophytes. 
Various  explanations  for  this  dissimilarity  have  been  considered 
by  the  author.  At  first  it  seemed  that  it  might  be  due  to  differ- 
ences in  soil  acidity,  but  all  the  forest  soils  tested  were  found  to 
be  more  or  less  acid  to  litmus.  Similarly,  differences  in  light  fail 
to  afford  an  adequate  explanation.  The  conclusion  has  finally 
been  reached  that  the  scarcity  of  mosses  and  liverworts  on  the 
forest  floor  in  deciduous  forests  is  correlated  in  large  measure 


Thuidium  delicatulum  cf 

Brachythecium  reflexum  cf 

Rhytidiadelphus  loreus  fc 

Rhytidiadelphus  triquetrus  fo 

Hylocomium  splendens  cf 

Hylocomium  umbratum  cf 

Ptilium  crista-castrensis  co 

Stereodon  cupressiformis  cf 

Heterophyllon  Haldanianum  cf 

Hypnum  Schreberi  cf 

Web  era  sessilis  fo 

P oly trichum  ohioense  cf 


Vegetation  of  Northern  Cape  Breton.  285 

with  the  deciduous  habit.  Every  year  the  ground  is  covered 
with  a more  or  less  continuous  blanket  of  fallen  leaves ; mosses 
and  liverworts  may  be  buried  alive,  so  to  speak,  and  repeated 
instances  have  been  observed  where  without  question  they  have 
been  partially  or  wholly  exterminated  in  this  way.  In  a general 
way  it  may  be  stated  that  in  the  climax  forests  of  northern  Cape 
Breton  the  abundance  of  bryophytes  is  inversely  proportional 
to  the  abundance  of  deciduous  trees. 

Reproduction  of  the  climax  trees. — In  the  normal  course  of 
events,  the  future  character  of  any  forest  is  determined  in  large 
measure  by  the  present  character  of  the  immature  trees.  The 
nature  of  the  rising  generation  may  be  said  to  furnish  a criterion 
of  permanency.  A permanent  forest  is  one  which  is  able  to 
perpetuate  itself.  It  is  therefore  a significant  fact  that  in  the 
primeval  forests  of  this  region  the  composition  of  the  younger 
generation  of  trees,  at  least  so  far  as  the  dominant  species  are 
concerned,  is  essentially  the  same  as  that  of  the  mature  stand. 
Beech,  sugar  maple,  birch,  and  red  maple  almost  everywhere 
exhibit  good  reproduction  underneath  the  forest  canopy.  The 
same  is  true,  more  locally,  of  the  oak  and  hemlock,  and  to  a less 
extent  of  the  ash  and  white  pine.  Reproduction  in  the  balsam 
fir  is  discussed  in  subsequent  paragraphs.  Young  trees  of 
paper  birch  and  white  spruce  are  seldom  found,  and  it  seems 
probable  that,  in  general,  they  either  represent  relicts  of  a more 
primitive  type  of  forest,  or  that  they  are  able  to  establish  them- 
selves only  under  the  more  favorable  light  relations  which  are 
occasionally  created  by  gaps  in  the  forest  canopy  overhead. 

The  ecological  relations  of  the  balsam  fir  in  the  climax  forest. 
- — The  balsam  fir  may  be  regarded  as  the  character  tree  of  the 
northeastern  evergreen  coniferous  climatic  forest  formation  (in 
this  connection,  see  especially  Cooper  ’13,  pp.  36-39).  In  parts 
of  Cape  Breton  where  this  climax  formation  holds  sway,  the 
balsam  far  outnumbers  all  other  trees.  In  the  competition  for 
supremacy  between  the  deciduous  and  the  evergreen  coniferous 
climax  forest-types,  the  balsam  fir,  in  this  region  at  any  rate, 
is  the  last  element  of  the  more  northern  type  of  forest  to  dis- 
appear. For  this  reason,  the  ecological  relations  of  this  tree  in 
the  climax  forests  of  the  lowland  have  been  given  considerable 
attention,  although  it  must  be  admitted  that  the  observations 
have  not  been  wholly  conclusive. 


286 


George  E.  Nichols, 


Seldom,  if  ever,  is  a tract  of  climax  forest  encountered  from 
which  the  balsam  fir  is  wholly  absent.  Frequently,  however,  it 
is  represented  only  in  the  younger  growth.  This  latter  condition 
is  well  brought  out  by  Table  V,  which  shows  the  relative 


TABLE  V 

Relative  Abundance  of  Various  Trees  in  Two  Quadrats  in  a Hard- 
wood Forest  along  the  Barrasois  River1 


Name  of  Species 

Diameter 
Less  than 
2 Inches 

Diameter 

2-5 

Inches 

Diameter 

t5T° 

Inches 

Diameter 
More  than 
10  Inches 

Fagus  grandifolia 

55 

5 

7 

3 

Acer  saccharum 

33 

O 

2 

2 

Betula  Intea 

2 

I 

1 

2 

Acer  r ub rum 

3 

O 

0 

I 

Abies  balsamea 

23 

O 

0 

O 

7 Quadrat  32.8  feet  (ten  meters)  square.  Figures  for  the  two  quadrats  are  added.  No  trees 
less  than  one  foot  high  counted. 


abundance  of  various  trees  on  two  quadrats  in  a hardwood  forest 
along  the  Barrasois  River  (Fig.  12).  The  most  interesting 
facts  to  be  deduced  from  this  table  are:  (1)  that,  of  the  trees 
less  than  five  inches  in  diameter  and  more  than  one  foot  high, 
balsam  fir  includes  18.5  per  cent,  (as  compared  with  beech,  50 
per  cent. ; sugar  maple,  26.6  per  cent. ; yellow  birch,  24  per 
cent.;  red  maple,  2.4  per  cent.);  while  (2),  of  the  trees  more 
than  five  inches  in  diameter,  none  at  all  are  balsam  (as  com- 
pared with  beech,  55.5  per  cent. ; sugar  maple,  22.2  per  cent. ; 
yellow  birch,  16.6  per  cent.;  red  maple,  5.5  per  cent.).  In  the 
mature  stand,  taken  as  a whole,  it  was  estimated  that  beech 
includes  fully  65  per  cent,  of  the  trees,  sugar  maple  and  yellow 
birch  each  about  15  per  cent.,  red  maple  and  paper  birch  together 
about  5 per  cent.  So  far  as  observations  extended,  no  mature 
balsam  fir  whatever  is  present,  the  largest  living  specimen  noted 
being  about  fifteen  feet  high;  but  several  dead,  standing  or 
fallen,  trunks  having  a diameter  of  about  eight  inches  were 
found.  The  larger  living  specimens  average  six  or  eight  feet 
in  height,  and  are  greatly  suppressed,  many  of  them  showing 
twenty-five  or  more  annual  rings. 

The  conditions  noted  in  this  tract  of  forest  are  essentially 
similar  to  those  which  prevail  in  many  other  areas : balsam  fir 


Vegetation  of  Northern  Cape  Breton.  287 

is  abundantly  represented  in  the  younger  generation,  but  is 
virtually  absent  from  among  the  mature  trees.  The  absence  of 
mature  balsam,  however,  is  far  from  being  the  rule.  In  the 
majority  of  cases  it  grows  along  with  the  more  southern  climax 
trees,  forming  an  important  constituent  of  the  stand,  and  con- 
tributing' to  the  formation  of  the  mixed  deciduous-evergreen 
forest  which  is  the  prevailing  climax  type  throughout  the  low- 
lands. In  competition  with  the  deciduous  climax  trees,  however, 
the  balsam  seldom  retains  a position  of  dominance,  and  occasional 
tracts  of  primeval  forest  are  encountered  in  which  not  only  all 
the  mature  trees,  but  practically  all  the  younger  ones  as  well, 
are  hardwoods  or  hemlock.  Forests  of  this  sort  are  essentially 
similar  to  the  type  which  formerly  prevailed  in  many  parts  of 
southern  New  England  (see  Nichols  T3). 

In  view  of  the  facts  set  forth  above,  the  query  naturally 
arises : Assuming  the  climatic  conditions  to  be  equally  favorable 
to  all  the  species  concerned,  why  is  it  that,  in  competition  with 
maple,  beech,  hemlock,  and  the  other  species  which  characterize 
the  deciduous  climax  forest,  the  balsam  fir  is  unable  to  hold  its 
own?  For  obvious  reasons  this  is  an  important  question,  and 
one  to  which  various  answers  may  be  suggested. 

(1)  The  relative  tolerance  of  shade  exhibited  by  the  various 
species  concerned,  at  first  thought,  seems  to  afford  the  most 
likely  explanation.  Beech,  sugar  maple,  and  hemlock  are 
notably  tolerant  species : they  are  capable  of  successful  repro- 
duction in  their  own  shade.  Regarding  the  tolerance  of  the 
balsam  fir  there  seems  to  be  a discrepancy  of  opinion.  According 
to  Cooper  (’13,  pp.  17-22,  42,  43),  the  balsam  demands  abundant 
light  for  successful  reproduction : “Later  in  life  the  young  trees 
can  endure  severe  shading,  but  for  a successful  start  abundant 
light  seems  to  be  a necessity.”  Zon  (’14,  p.  39),  on  the  other 
hand,  states  that,  “For  the  first  five  or  six  years  of  its  life, 
balsam  will  grow  in  dense  shade,  but  as  it  develops  it  demands 
more  and  more  light.”  In  northern  Cape  Breton,  the  sparsity 
of  balsam  seedlings  and  young  trees  in  many  hardwood  tracts 
might  well  harmonize  with  Cooper’s  conclusions,  were  it  not  for 
the  fact  that  in  other  equally  shady  forests  the  young  balsam 
growth  is  quite  abundant.  In  this  connection  the  observation 
of  Moore  (’17,  p.  157),  made  on  Mount  Desert  Island,  that, 
“Under  many  spruce  stands  which  have  reached  about  middle 


288 


George  E.  Nichols, 


age,  the  fir  reproduction  is  nearly  all  composed  of  large  seedlings 
approximately  1-3  feet  in  height;  young  seedlings  are  scarce,” 
is  of  interest.  As  indicated  above,  parallel  conditions  have 
frequently  been  observed  in  the  lowland  climax  forests  of  north- 
ern Cape  Breton.  Moore  suggests  that,  “In  these  cases  it 
appears  that  the  fir  came  in  profusely  under  a set  of  environmen- 
tal conditions  different  from  the  present  ones  ....  One  of 
them  may  have  been  stronger  light  than  at  present.  Indications 
of  this  were  found  in  the  fact  that  some  of  these  cases  of  fir 
reproduction  occur  in  stands  which  were  formerly  more  open 
than  they  are  now.”  In  one  striking  case  of  this  sort,  observed 
by  the  writer,  the  abundance  of  young  balsam  in  a primeval 
hardwood  forest  is  certainly  correlated  with  the  occurrence, 
about  fifteen  years  ago,  of  a fire  which,  while  it  was  not  suffi- 
ciently severe  to  seriously  injure  the  larger  trees,  must  have 
resulted  temporarily  in  a considerably  increased  illumination 
of  the  forest  floor.  Certain  it  is  that  the  balsam  reproduces 
best  and  grows  most  vigorously  in  well-lighted  situations,  and 
there  seems  to  be  little  question  that  it  is  less  tolerant  of  shade 
than  sugar  maple,  beech,  and  hemlock.  Nevertheless,  repeated 
observations  have  led  to  the  conclusion  that  at  any  rate  tolerance 
alone,  even  in  the  broadest  interpretation  of  the  term  (see 
Burns  ’16,  pp.  3,  4,  22),  cannot  be  regarded  'as  the  cause  for 
the  elimination  of  the  balsam. 

(2)  It  has  been  suggested  by  Murphy  (’17)  that  the  burial 
of  the  seeds  of  the  spruce  by  a mulch  of  hardwood  leaves  may 
be  a very  important  factor  in  the  suppression  of  this  tree  in 
competition  with  deciduous  trees.  That  the  yearly  accumulation 
of  leaf  litter  on  the  floor  of  a deciduous  forest  is,  in  a some- 
what similar  manner,  responsible  for  the  poor  development  of 
the  bryophytic  ground  cover,  was  a conclusion  already  arrived 
at  by  the  writer  (see  page  284);  and  it  seems  not  impossible 
that  this  may  also  be  a factor  of  some  significance  as  affecting 
the  reproduction  of  the  balsam  fir. 

(3)  In  the  opinion  of  the  writer,  however,  longevity,  in  the 
last  analysis,  is  the  critical  factor  which  enables  the  maple,  beech, 
hemlock  and  the  associated  climax  trees  of  the  deciduous  forest 
climatic  formation  of  eastern  North  America  to  win  out  in 
competition  with  the  balsam  fir.  In  this  connection,  the  behavior 
of  the  hemlock,  as  studied  in  the  primeval  forests  of  north- 


Vegetation  of  Northern  Cape  Breton.  289 

western  Connecticut  (see  Nichols,  ’13),  is  enlightening.  The 
hemlock  is  capable  of  growing  in  a suppressed  condition  under 
the  shade  of  other  trees  for  more  than  a century.  A tree  which 
has  been  thus  suppressed  may  have  attained  at  the  end  of  a 
hundred  years  a diameter  of  perhaps  six  or  eight  inches  and 
may  have  grown  well  up  into  the  forest  canopy  overhead.  With 
the  improvement  of  light  conditions,  which  may  be  accomplished 
either  through  its  own  upward  growth  or  through  the  down- 
fall of  contiguous  trees,  such  a tree  grows  vigorously,  and 
may  attain  an  age  of  more  than  300  years,  with  a diameter  of 
more  than  four  and  a height  of  more  than  a hundred  feet, 
before  its  death  is  brought  about  through  disease,  wind,  or  other 
agency.  What  is  said  of  the  hemlock  applies  also  to  the  sugar 
maple  and  beech,  although  these  trees  are  perhaps  more 
susceptible  to  disease  than  the  hemlock.  The  behavior  of  the 
balsam  fir  is  in  marked  contrast.  Although,  like  the  hemlock, 
the  balsam  is  able  to  grow  for  many  years  in  fairly  dense  shade, 
it  is  handicapped  by  its  susceptibility  to  fungus  diseases,  largely 
in  consequence  of  which  its  lease  on  life  is  limited.  At  the 
age  of  a hundred  years,  a hemlock,  even  if  it  has  been  grow- 
ing suppressed  all  this  time,  will  usually  have  a sound,  healthy 
trunk.  In  northern  Cape  Breton,  at  any  rate,  the  balsam  fir, 
even  under  favorable  conditions,  seldom  reaches  the  age  of 
seventy  years  without  having  become  infected  by  heart  rot,s 
and  by  the  time  it  has  rounded  the  century  mark  its  trunk  usually 
has  become  badly  rotted  within.  In  addition  to  the  “ground 
rot,”  which,  in  conjunction  with  the  brittleness  of  the  wood, 
renders  the  tree  liable  to  windfall  (Fig.  13),  the  balsam  fir, 
when  growing  in  a suppressed  condition  under  hardwoods,  is 
likely  to  be  affected  by  “top  rot,”  which  may  cause  it  to  die  back 
from  the  top.  Like  the  hemlock,  however,  a balsam  may  ulti- 
mately find  an  opening  in  the  forest  canopy  overhead.  But  by 


B According  to  Zon  (’14),  two  species  of  fungi  are  concerned:  Trametes 
Pini  (Brot.)  Fr.  and  Polyporus  Schweinitzii  Fr.,  which  may  cause  either 
“ground  rot”  or  “top  rot.”  According  to  the  observations  of  Dr.  G.  P. 
Clinton  in  the  western  Adirondacks,  and  of  the  writer  in  northwestern 
Maine  and  northern  Cape  Breton,  in  these  regions  heart-rot  in  the  balsam 
fir  seems  to  be  attributable  to  still  another  fungus,  Fomes  pinicola  Fr.,  a 
species  which  Duggar  (’09,  p.  467)  has  also  mentioned  as  one  which 
causes  disease  in  the  balsam. 


290 


George  E.  Nichols, 


this  time  it  is  an  old  tree.  For,  while  the  hemlock  at  a hundred 
years  is  still  comparatively  young,  the  balsam  is  already  a veteran, 
since  (at  least  in  northern  Cape  Breton)  it  seldom  lives  to  be 
more  than  125  years  old. 

To  sum  up,  if  it  is  assumed  that  the  climatic  conditions  are 
equally  favorable  to  all  the  species  concerned,  the  apparent 
inability  of  the  balsam  fir  to  compete  successfully  with  the 
species  which  characterize  the  deciduous  climax  forest  formation 


Figure  13. — Wind-fellfed  balsam  fir;  Adirondack  Mountains,  New  York. 
The  specimen  in  the  background  shows  the  manner  in  which  the  trunk 
commonly  splinters. 

can  be  attributed  in  large  part  to  its  shorter  tenure  of  life, 
coupled  with  which  are  its  greater  susceptibility  to  fungus 
diseases  and  its  less  pronounced  tolerance  of  shade.  That  the 
climate  in  this  region  is  favorable  to  the  deciduous  climax  trees 
is  attested  by  their  vigorous  growth  and  the  large  size  which 
they  commonly  attain.  That  it  is  favorable  to  the  balsam  fir  is 
manifest  from  the  manner  in  which  this  tree  thrives  wherever 
there  is  freedom  from  competition.  It  should  be  added  that,  con- 
sidering the  transition  region  in  its  entirety,  account  must  also 
be  taken  of  climate.  Climatic  factors  without  doubt  have  been 


Vegetation  of  Northern  Cape  Breton.  291 

of  great  importance  during  the  northward  migration  of  the 
deciduous  climax  trees  which  has  ensued  in  post-glacial  time 
(see  especially  Adams  ’02),  and  there  is  little  question  that  in 
parts  of  the  transition  region  farther  south,  where  balsam  is 
absent  or  restricted  in  its  distribution,  such  factors  are  still  of 
large  significance. 

General  features  of  transition  climax  forests  in  northern  Cape 
Breton  and  elsewhere. — The  trees  which  characterize  forests  of 
the  climax  type  in  the  lowland  of  northern  Cape  Breton  may  be 
divided  into  four  groups,  as  follows:  (A)  Deciduous  species, 

such  as  the  beech  and  sugar  maple,  whose  center  of  distribution 
lies  south  of  the  transition  region;  ( B ) Deciduous  species, 
notably  the  yellow  birch,  whose  center  of  distribution  lies  within 
the  transition  region;  (C)  Evergreen  species,  notably  the  hem- 
lock, whose  center  of  distribution  lies  within  the  transition 
region;  and  (D)  Evergreen  species,  such  as  the  balsam  fir  and 
white  spruce,  whose  center  of  distribution  lies  north  of  the 
transition  region.  To  these  might  perhaps  be  added  a fifth  group : 
(E)  Deciduous  species,  such  as  the  paper  birch  and  the  balsam 
poplar,  whose  center  of  distribution  lies  north  of  the  transition 
region. 

It  has  been  intimated  in  earlier  paragraphs  that  the  relative 
abundance  of  the  different  climax  trees  is  subject  to  considera- 
ble local  variation.  By  way  of  summary,  it  may  be  stated  that 
in  forests  of  the  regional  climax  type  the  trees  of  group  A com- 
monly predominate,  though  sometimes  they  are  outnumbered  by 
those  of  group  C.  The  yellow  birch,  representing  group  B,  is 
practically  always  present,  varying  greatly  in  abundance,  usually 
common  though  seldom  predominant  (but  see  in  this  connection 
p.  387).  The  trees  of  group  D are  seldom  completely  absent: 
usually  they  occupy  a prominent,  but  rarely  a predominant,  posi- 
tion in  the  forest.  The  trees  of  group  E are  commonly  repre- 
sented, but  always  as  a minor  element  in  the  forest:  frequently 
they  are  missing  altogether. 

While  the  above  observations  are  made  primarily  with  refer- 
ence to  conditions  in  northern  Cape  Breton,  they  are  capable  of 
much  wider  application.  Throughout  much  of  the  vast  expanse 
in  eastern  North  America  which  is  embraced  by  the  transition 
region,  the  five  groups  of  trees  specified  in  the  preceding  para- 
graph are  represented.  Broadly  speaking,  throughout  this  area 


292 


George  E.  Nichols, 


the  nature  of  the  regional  climax  forests  is  essentially  similar, 
in  so  far  as  their  ecological  aspect  is  concerned;  but,  just  as 
in  Cape  Breton,  there  is  considerable  local  variation  in  their 
composition — in  the  presence  or  absence  of  certain  species  and 
in  their  relative  abundance  when  present.  Leaving  out  of  con- 
sideration the  species  of  the  fifth  group,  which  occupy  a rela- 
tively insignificant  position  here,  it  is  possible  to  distinguish, 
with  reference  to  the  presence  or  absence  in  the  forest  of  mem- 
bers of  the  first  four  groups  outlined  above,  eleven  different 
group-combinations  of  trees  which  may  comprise  an  equal 
number  of  floristically  different  types  of  climax  forest.  Indicat- 
ing the  respective  groups  by  letter,  these  various  group-combina- 
tions are  as  follows:  (x)  A-B ; (2)  A-B-C ; (3)  A-B-C-D; 
(4)  A-B-D;  (5)  A-C;  (6)  A-C-D ; (7)  A-D ; (8)  B-C ; (9) 
B-C-D;  (10)  B-D;  (11)  C-D. 

In  sections  of  the  country  where  all  four  groups  of  climax 
trees  (A,  B,  C,  D)  are  well  represented,  forests  comprising  any 
and  each  of  these  group-combinations  may  be  encountered.  As 
might  be  expected,  however,  while  the  trees  of  groups  B and  C 
are  about  equally  well  represented  'in  forests  throughout  the 
transition  region,  those  of  group  A are  most  generally  repre- 
sented southward,  those  of  group  D northward.  It  is  along  the 
southern  borders  of  the  transition  region,  in  that  part  of 
the  area  where  climatic  conditions  presumably  are  most  favorable 
to  the  trees  of  group  A (and  least  so  for  those  of  group  D ), 
and  which  these  have  occupied  for  the  longest  time  that  the  first 
group-combination  (A-B:  the  “northern  hardwood”  type  of 
forest)  is  most  extensively  developed.  Here  the  trees  of  group 
D tend  to  be  localized  in  situations  which  are  edaphicallv 
favorable : they  develop  best  in  areas  which  are  somewhat 
swampy.  Conversely,  along  the  northern  borders  of  the  transi- 
tion region,  in  that  part  of  the  area  where  climatic  conditions 
presumably  are  less  favorable  for  the  deciduous  species  of 
group  A (but  more  so  for  those  of  group  D),  or  which,  it  may 
be,  these  species  in  their  post-glacial  migration  have  reached  only 
in  comparatively  recent  time,  the  trees  of  group  D are  commonly 
a conspicuous  and  even  the  predominant  element  in  forests  of 
the  regional  climax  type.  Here  the  trees  of  group  A tend  to  be 
restricted  to  the  better  drained  soils.  It  is  important  to  note 
in  this  connection,  however,  that  even  along  the  northern 


Vegetation  of  Northern  Cape  Breton.  293 

border  of  the  transition  region,  as  in  Cape  Breton,  purely 
deciduous  forests  are  by  no  means  lacking,  and  that  the  trees  of 
group  A growing  here  compare  quite  favorably  in  size,  vigor 
and  ability  to  reproduce  themselves  with  those  growing  in 
forests  farther  south.  It  is  of  further  interest  that  along  the 
southern  border  of  the  transition  region  the  trees  of  group  D 
may  occupy  a prominent  position  in  climax  forests : in  one 
locality  in  northwestern  Connecticut,  for  example,  at  an  eleva- 
tion of  less  than  2,000  feet,  the  black  spruce  is  thriving  on 
uplands,  reproducing  well,  attaining  a large  size,  and  growing 
in  association,  not  only  with  beech  and  maple,  birch  and  hemlock, 
but  with  such  species  as  chestnut  ( Castanea  dentata ) and 
mountain  laurel. 

Considerable  interest  attaches  itself  to  the  relative  importance, 
in  transition  forests  where  the  trees  of  group  D are  represented, 
of  the  balsam  fir  and  black  spruce.  In  northern  Michigan 
(Whitford  ’01),  Ontario  (Howe  & White  ’13),  and  elsewhere 
the  balsam  fir,  as  in  Cape  Breton,  seems  to  be  the  predominant 
northern  conifer.  But  in  other  localities  the  black  spruce 
occupies  the  position  of  relative  predominance.  This  seems  to 
be  true,  to  cite  localities  with  which  the  author  is  personally 
familiar,  in  the  western  Adirondacks  and  in  northwestern 
Maine.  In  the  primeval  forests  about  Big  Moose  (elevation 
about  2,000  feet),  in  the  Adirondacks,  for  example,  where  it 
grows  abundantly,  in  company  with  beech,  sugar  maple,  yellow 
birch,  and  hemlock,  the  black  spruce  attains  a diameter  of  more 
than  three,  and  a height  of  more  than  125  feet.  Here,  as  in 
Maine,  the  balsam  fir  is  present  in  the  forest,  but  it  is  more 
characteristic  of  the  “flats”  and  moister  sites.  As  noted  earlier, 
the  black  spruce  is  represented  in  the  climax  forests  of  the  low- 
land in  northern  Cape  Breton,  but  here  it  is  infrequent  and 
never  reaches  the  size  exhibited  by  the  spruce  in  the  Adirondacks. 

In  proceeding  northward  from  the  region  of  deciduous 
forests  to  that  of  coniferous  forests  (Fig.  i)  there  is  a gradual 
transition  from  one  type  of  forest  to  the  other.  Broadly  speak- 
ing, however,  due  largely  to  the  predominating  influence  of  the 
deciduous  element,  forests  of  the  regional  climax  type  are 
essentially  similar  in  their  ecological  aspect  throughout  the 
transition  region.  Various  attempts  have  been  made  to  define 
subdivisions  of  this  region  on  the  basis  of  veg'etational  dissimi- 


294  George  E.  Nichols, 

larities,  but  while  such  subdivisions  may  be  of  floristic  impor- 
tance, their  significance  from  the  standpoint  of  ecological  plant 
geography  is  at  least  open  to  question.  Thus,  it  is  doubtful 
whether  the  “Northern  Mesophytic  Evergreen  Forest”  region 
(characterized  in  the  east  by  the  presence,  as  the  most  common 
species,  of  white  pine,  hemlock,  jack  pine  [Pimis  Banksiana ] 
and  balsam  fir),  which  Shreve  (T 7)  maps  as  distinct  from  the 
“Northeastern  Evergreen-Deciduous  Transition  Forest”  region, 
should  be  so  separated,  since  throughout  this  area,  as  elsewhere 
in  the  transition  region,  climax  forests  of  the  deciduous  type  are 
commonly  encountered  in  situations  which  are  edaphically  suited 
to  their  development.  Similarly,  the  “White  Pine  Region”  of 
New  England,  as  mapped  by  Hawley  and  Hawes  (’12),  while 
distinct  from  the  standpoint  of  the  forester,  does  not  seem  to 
be  so  from  the  standpoint  of  ecological  plant  geography.  White 
pine  is  a frequent  constituent  of  the  climatic  climax  forest 
throughout  the  transition  region ; but,  when  growing  in  pure 
stands,  it  probably  represents  either  a temporary  association  or 
else  an  edaphic  climax.  Not  only  does  it  appear  unwarranted, 
from  the  standpoint  of  ecological  plant  geography,  to  recognize 
such  subdivisions  as  distinct,  but,  as  elsewhere  suggested 
(p.  261),  from  this  point  of  view  the  vegetation  of  the  transi- 
tion region  itself  is  best  regarded  merely  as  a part  of  the  great 
deciduous  forest  climatic  formation  of  eastern  North  America. 

II.  THE  EDAPHIC  FORMATION-COMPLEX  OF  THE  REGION 
A.  Primary  Formations  of  the  Xerarch  Series 

1.  The  Formation-types  of  Ordinary  Uplands 

a.  introductory 

In  attempting  to  formulate  the  successful  series  which  lead 
toward  and,  under  favorable  circumstances,  culminate  in  the 
climax  association-type  of  the  region,  there  are  three  possible 
sources  of  evidence:  (/)  areas  in  which  succession  is  actually 
taking  place  at  the  present  time  (or  has  taken  place  within  com- 
paratively recent  times),  as  indicated  more  particularly  by  the 
presence  of  (a)  relicts  of  more  primitive  associations,  or  ( b ) 
pioneers  of  more  advanced  associations  than  the  present  ones ; 


Vegetation  of  Northern  Cape  Breton.  295 

(2)  areas  in  which,  owing  to  the  limiting  influence  of  certain 
local  factors,  the  succession  has  culminated  in  an  edaphic  climax 
which  is  less  mesophytic  than  the  regional  climax  association- 
type;  and  (3)  areas  which  have  been  denuded  of  their  original 
vegetation,  and  where  secondary  succession  is  taking  place. 
Secondary  successions  are  discussed  in  a separate  section,  but 
they  obviously  possess  many  points  in  common  with  primary  suc- 
cessions. 

Aside  from  the  views  of  the  regional  climax  forest  (Figs. 
10— 1 1 ) , the  primary  formation-types  of  ordinary  uplands  are 
pictured  only  by  Figs.  14-16;  but  see  in  this  connection  the 
figures  illustrating  secondary  formations  (Figs.  33-40). 

b.  THE  ASSOCIATION-COMPLEXES  OF  ROCK  OUTCROPS 

Rock  surface  association-types. — The  first  forms  of  life  to 
grow  on  a bare  rock  surface  are  usually  the  lichens.  Commonly 
the  crustose  lichens  appear  first:  species  of  Buellia,  Lecanora, 
Lecidia,  Rhizocarpon,  etc.  These  are  closely  followed  and  often 
accompanied  by  foliose  lichens : species  of  Parmelia,  Gyrophora, 
etc.  Associated  with  these  may  be  the  fruticose  lichen,  Stereo- 
caulon  sp.,  and  certain  lithophytic  mosses,  such  as  Hedwigia 
ciliata  and  Grimmia  afocarpa.  Where  the  rock  slopes  steeply, 
other  plants  may  be  entirely  absent,  owing  to  their  inability  to 
secure  a foothold  on  the  bare  rock  surface,  and  the  succession 
may  become  arrested  at  this  early  stage. 

But  on  gentle  slopes  the  conditions  are  different,  for  here 
plants  are  able  to  maintain  their  positions  even  when  entirely 
unattached  to  the  substratum.  Situations  of  this  sort  are 
favorable  to  the  development  of  the  fruticose  lichens,  notably 
species  of  Cladonia  (e.  g.,  C.  rangiferina,  C.  sylvatica ).  These 
usually  establish  themselves  first  in  shallow  depressions  of  the 
rock  surface,  where  moisture  conditions  are  relatively  favorable, 
and  from  here  they  may  spread  laterally  in  all  directions  until 
the  surface  of  the  rock  becomes  completely  covered  with  a loose, 
essentially  unattached  mat  of  vegetation.  In  company  here 
with  the  fruticose  lichens  very  commonly  grow  certain  mosses  : 
these  may  include  any  of  the  species  mentioned  below  as  charac- 
teristic of  crevices,  but  particularly  Racomitrium  canescens  and 
species  of  Polytrichum. 


296 


George  E.  Nichols, 


Crevice  association-types. — Contemporaneously  with  the  rock 
surface  “subsuccession”  (Cooper  ’13,  p.  118)  occurs  the  crevice 
“subsuccession.”  In  the  crevices,  and  also,  to  some  extent,  in 
hollows  of  the  rock  surface,  a soil  is  usually  present,  and  this 
enables  plants  to  grow  which  are  unable  to  secure  a foothold  on 
a rock  surface  or  to  maintain  themselves  in  such  an  environment. 
The  pioneer  crevice  vegetation  may  include  the  fruticose  lichens 
already  mentioned  as  growing  on  rock  surfaces.  It  may  also 
include  various  mosses,  such  as  Ceratodon  purpureas,  Leuco- 
bryum  glaucum,  Dicranum  scoparium  and  D.  Bonjeanii,  and 
Polytrichum  piliferum.  But  more  important  than  these,  in  the 
light  of  subsequent  events,  are  the  ferns  and  seed  plants.  Of 
the  ferns,  Pteris  aquilina  is  the  most  frequent  crevice  form, 
although  Polypodium  vulgare  often  grows  here,  in  sheltered 
situations.  Among  the  more  important  herbaceous  seed  plants 
which  inhabit  crevices  may  be  cited  Potentilla  tridentata,  which 
seldom  grows  anywhere  else,  Deschampsia  flexuosa  and  Dan- 
thonia  spicata,  Cornus  canadensis,  and  Solidago  bicolor.  Of  the 
shrubby  and  semi-shrubby  seed  plants,  Vaccinitim  pennsyl- 
vanicum,  V.  canadense,  and  Gaultheria  procumbens  are  rarely 
absent,  while  Vaccinium  Vitis-Idaea  is  especially  characteristic 
of  such  habitats.  Almost  any  of  the  trees  to  be  mentioned 
presently  as  occurring  on  the  heath  mat  may  be  found  in 
crevices.  In  a sense  there  may  appear  to  be  a succession  of 
growth  forms  in  crevices,  herbs  preceding  shrubs,  etc.,  but  suc- 
cession of  this  sort,  on  the  whole,  is  probably  more  apparent  than 
real. 

The  heath  association-type. — Up  to  a certain  point,  the  rock 
surface  and  the  crevice  “subsuccessions”  are  distinct  from  one 
another.  But  with  the  formation  of  the  lichen-moss  mat  over 
the  rock  surface,  and  the  gradual  accumulation  of  soil  which 
accompanies  the  process,  the  two  tend  to  merge  into  one.  The 
various  seed  plants,  particularly  the  shrubs,  which  hitherto  have 
been  largely  confined  to  the  crevices,  become  increasingly 
abundant  over  the  rock  surface,  and  ultimately  there  may  arise 
what  Cooper  has  aptly  termed  a “heath  mat”  (’13,  p.  125).  Here 
the  ground  is  still  covered  by  a mat  of  fruticose  lichens  and 
mosses,  but  these  are  no  longer  the  dominant  plants.  As  such 
they  have  been  superseded  by  ferns  and  seed  plants,  whose  roots 
tend  to  bind  together  the  hitherto  loose  mat  and  to  consolidate  it 


Vegetation  of  Northern  Cape  Breton. 


297 


into  a more  or  less  compact  turf.  The  predominant  plants  of 
the  heath  association-type  are  low  shrubs,  particularly  Ericaceae. 
A list  of  species  characteristic  of  this  phase  in  the  succession  is 
given  below. 

Herbaceous  Plants 

Pteris  aquilina  Cornus  canadensis 

D eschampsia  flexuosa  Melampyrum  lineare 

Danthonia  spicata  Solidago  bicolor 


Shrubby  and  Semi-shrubby  Plants 
Juniperus  communis  depressa  Kalmia  angustifolia 


Juniperus  horizontalis 
Salix  humilis 
Alnus  crispa 
Amelanchier  sp. 
Empetmm  nigrum 
Nemopanthus  mucronata 
Rhododendron  canadense 


Gaultheria  procumbens 
Epigaea  repens 
Gaylussacia  baccata 
Vaccinium  pennsylvanicum 
Vaccinium  canadense 
Vaccinium  Vitis-Idaea 
Viburnum  cassinoides 


Pinus  Strobus 
Abies  balsamea 
Picea  canadensis 
Picea  mariana 


Trees 

Betula  alba  papyri f era 
Pyrus  americana 
Primus  pennsylvanica 
Acer  rubrum 


As  a rule  the  dominant  shrub  of  the  heath  mat  is  Vaccinium 
pennsylvanicum.  But  Vaccinium  canadense  may  be  equally 
abundant ; while  in  some  places  the  Kalmia  forms  an  almost 
pure  growth,  or  may  grow  mixed  with  Rhododendron.  Gaul- 
theria  and  Epigaea  usually  form  a lower  story  of  vegetation ; and 
the  same,  locally,  is  true  of  Vaccinium  Vitis-Idaea.  Empetrum 
is  particularly  characteristic  of  exposed  bluffs  along  the  seacoast, 
and  will  be  referred  to  again  in  that  connection.  Occasionally 
the  grasses,  Danthonia  spicata  and  Deschampsia  flexuosa,  are 
dominant  forms. 

The  coniferous  forest  association-type. — As  already  pointed 
out,  trees  may  inhabit  the  crevices  at  an  early  stage  in  the  suc- 
cession. With  the  improvement  of  soil  relations  which  results 


Trans.  Conn.  Acad.,  Vol.  XXII 


1918 


20 


2g8 


George  E.  Nichols, 


from  the  mantling  of  the  rock  surface  by  a mat  of  vegetation, 
they  cease  to  be  confined  to  crevices  and  invade  the  areas 
between.  At  first  few  and  scattered,  they  gradually  increase  in 
number  and  size  and  come  to  occupy  the  ground  more  com- 
pletely. In  the  course  of  time,  groups  of  trees  in  the  more 
favorable  situations  form  patches  of  embryonic  woodland,  and, 
as  these  spread  and  unite  with  one  another,  a more  or  less  con- 
tinuous forest  may  be  evolved.  Not  infrequently  trees  come  in 
so  rapidly  and  in  such  force  at  the  outset  that  the  heath  stage 
in  the  succession  is  virtually  eliminated.  The  succession  does  not 
proceed  with  equal  rapidity  everywhere,  even  within  a given 
physiographic  unit  area.  For,  owing  to  locally  unfavorable 
edaphic  conditions,  succession  in  some  situations  lags  behind  that 
in  others,  with  the  result  that  there  commonly  arises  a complex 
of  associations,  in  which  various  stages  in  the  developmental 
series  are  represented.  This  promiscuous  intermingling  of  primi- 
tive and  advanced  associations  becomes  less  pronounced  as  time 
goes  on,  but  even  in  the  midst  of  a climax  forest  there  may  be 
situations  in  which  succession  has  never  progressed  beyond  the 
rock  face-crevice  stage. 

During  the  early  phases  of  forest  development,  the  white 
spruce  commonly  stands  out  as  the  predominant  tree : the  balsam 
fir,  as  a rule,  is  second  in  importance.  Common  associates  in  the 
rising  forest  are  the  paper  birch,  conspicuous  by  reason  of  its 
light  color  and  large  size ; the  black  spruce,  red  maple,  and 
mountain  ash ; and,  less  commonly,  the  white  pine.  As  the  forest 
matures,  the  relative  importance  of  the  two  dominant  trees 
undergoes  certain  changes,  due  very  largely  to  the  differing 
degree  to  which  the  two  are  tolerant  of  shade.  The  white  spruce 
is  a relatively  intolerant  species.  Its  seedlings  thrive  only  in 
situations  where  there  is  abundant  light.  While  it  reproduces 
prolifically  in  the  open,  young  trees  are  rarely  encountered  in  the 
forest.  The  balsam  fir,  on  the  other  hand,  is  relatively  tolerant 
of  shade.  Like  the  white  spruce,  it  reproduces  best  in  well 
lighted  situations,  but  unlike  the  white  spruce  its  seedlings  are 
also  capable  of  thriving  in  moderate  shade.  The  result  is 
obvious.  With  the  diminished  illumination  of  the  forest  floor 
which  accompanies  the  growth  of  the  forest,  there  is  a marked 
decrease  in  the  rate  of  reproduction  of  the  white  spruce,  while 
the  balsam  fir  is  much  less  affected.  It  follows  that,  as  the 


Vegetation  of  Northern  Cape  Breton.  299 

forest  matures,  the  white  spruce  tends  to  become  relatively  less 
abundant,  the  balsam  fir  relatively  more  so. 

Contemporaneously  with  the  ever-increasing  amount  of  shade 
produced  by  the  canopy  of  foliage  overhead,  the  vegetation  of  the 
forest  floor  also  changes.  The  cladonias  of  the  heath  stage  are 
largely  superseded  by  bryophytes.  Of  the  mosses,  Hypnum 
Schreberi  is  the  pioneer  forest  species  and  often  appears  on  the 
heath  mat  well  in  advance  of  the  forest  itself.  Along  with  this, 
but  much  less  common,  may  grow  Rhytidiadelphus  triquetrus. 
As  the  shade  and  moisture  conditions  on  the  forest  floor  become 
more  favorable,  two  relatively  mesophytic  mosses,  Hylocomium 
splendens  and  Ptilium  crista-castrensis,  together  with  the  liver- 
wort, Bazzania  trilobata,  come  to  play  an  important  part  in  the 
formation  of  the  moss  carpet,  by  which  the  ground  sooner  or 
later  becomes  almost  completely  covered  over.9  Of  the  shrubs 
and  herbaceous  vascular  plants  'which  are  characteristic  of  the 
heath  mat,  certain  species,  such  as  Pteris  aquilina , Cornns  cana- 
densis, Epigaea  repens,  Vaccinium  pennsylvanicum  and  V. 
canadense,  are  equally  characteristic  of  the  coniferous  forest, 
particularly  during  the  early  phases  of  its  development. 
Coincident  with  the  formation  of  the  moss  carpet,  however, 
other  species  begin  to  appear  which,  while  they  may  have  been 
represented  to  some  extent  in  the  earlier  stages  of  the  succession, 
are  more  typical  of  the  forest.  The  forerunners  include  Maian- 
themum  canadense,  Aralia  nudicaulis,  Pyrola  secunda,  Trientalis 
americana,  Chiogenes  hispidula,  and  Linnaea  borealis  americana. 
Later  on,  as  the  forest  matures,  these  relatively  xero-mesophytic 
forms  are  followed  by  other  species  which  are  more  truly  meso- 
phytic, such  as  Clintonia  borealis,  Coptis  trifolia,  Oxalis  Aceto - 
sella,  Moneses  uniflora,  Pyrola  minor,  and  Aster  acuminatus. 

Very  often,  during  the  early  development  of  a coniferous 
forest  there  is  a considerable  period  when  the  ground  underneath 
the  trees  is  almost  barren  of  a plant  cover.  The  probable 
explanation  of  this  frequently  observed  phenomenon  is  suggested 
later  in  connection  with  the  discussion  of  succession  in  abandoned 
pastures. 

The  edaphic  climax  association-type. — Theoretically,  at  least, 


9 Cooper  (’11)  has  described  a similar  succession  of  lichens  and  mosses 
as  accompanying  the  development  of  the  climax  forest  on  Isle  Royale. 


3°° 


George  E.  Nichols, 


it  is  conceivable  that  even  on  a bare  rock  surface,  through  the 
gradual  amelioration  of  the  habitat  by  biotic  factors,  the  succes- 
sion of  plant  associations  might  progress  still  further,  and  that 
the  vegetation  here  might  ultimately  attain  tbe  condition  which 
characterizes  the  climax  association-type  of  the  region.  But,  as 
a matter  of  fact,  on  bare  rock  outcrops  the  succession  seldom 
proceeds  further  than  the  coniferous  forest  stage.  In  other 
words,  the  coniferous  forest  can  be  regarded  as  representing  the 
edaphic  climax  association-type  of  the  rock  outcrop  successional 
series : it  is  a permanent  association-type,  though  ordinarily  less 
mesophytic  than  the  regional  climax  association-type  (in  this 
connection,  see  Nichols  ’17,  pp.  310-317).  In  its  optimum  devel- 
opment, the  coniferous  forest  association-type  of  the  rock  out- 
crop series  in  the  lowland  may  resemble  very  closely  the  climatic 
climax  of  the  mountains,  and  indeed  it  may  be  quite  as  mesophytic 
as  the  regional  climax  type.  Balsam  fir  is  the  predominant  tree, 
while  white  spruce,  paper  birch,  black  spruce,  white  pine,  red 
maple,  yellow  birch,  and  mountain  ash  are  more  or  less  abundantly 
represented.  But,  as  has  already  been  suggested,  such  may  be 
the  effect  of  the  limiting  edaphic  factors  that  in  many  places  the 
succession  halts  at  a much  earlier  stage  than  this. 

C.  THE  ASSOCIATION  COMPLEXES  OF  GLACIAL  DRIFT 

Extensive  outcrops  of  bare  rock  are  seldom  encountered  in 
the  lowland.  The  most  widespread  type  of  substratum  here  is 
glacial  drift.  The  drift,  to  perhaps  a greater  degree  than  any 
other  type  of  substratum,  is  well  adapted  to  rapid  colonization  by 
plants.  So  favorable,  indeed,  were  the  original  conditions  here, 
and  so  rapidly  has  the  succession  of  plant  associations  ensued,  that 
the  drift  everywhere  has  long  since  become  covered  by  forests. 
It  is  only  where  the  original  plant  cover  has  been  destroyed, 
either  through  the  agency  of  stream  or  wave  erosion,  or  else  as 
the  result  of  human  activity  or  fire,  that  the  earlier  phases  of  the 
succession  become  apparent.  The  early  stages  of  primary  suc- 
cessional series  on  drift  can  be  reconstructed  by  analogy,  after 
a fashion,  from  the  study  of  primary  successions  on  other  sub- 
strata and  of  secondary  successions  on  the  drift. 

Coniferous  forest  locally  an  edaphic  climax. — Disregarding  for 
the  present  the  earlier  phases  of  the  succession,  suffice  it  to  state 
that  eventually  there  may  arise  on  the  drift  a type  of  forest  essen- 


Vegetation  of  Northern  Cape  Breton.  301 

tially  similar  to  what  has  been  described  above  as  constituting 
the  ultimate  phase  in  the  rock  outcrop  series : a forest  of 
balsam  fir,  white  spruce,  paper  birch,  etc.  And  it  is  of  interest 
to  note  that,  locally,  such  a forest  may  also  constitute  an  edaphic 
climax,  even  on  the  drift.  In  the  vicinity  of  Baddeck,  for 
example,  over  most  of  the  country  succession  has  never  pro- 
gressed beyond  the  coniferous  forest  stage.  This  circumstance, 
without  much  question,  is  correlated  with  the  heavy,  clayey 
nature  of  the  drift  here,  which  has  acted  as  a limiting  factor  to 
prevent  the  attainment  of  the  regional  climax.  It  is  of  further 
interest  in  this  connection  that  around  Baddeck,  and  in  certain 
other  localities  where  the  soil  is  heavy,  the  tamarack  ( Larix 
laricina ) is  an  important  arborescent  pioneer  and  a constituent 
of  the  coniferous  forest.  Throughout  much  of  northern  Cape 
Breton  the  tamarack  is  a rarity.  Its  ecological  status  will  be 
referred  to  again  in  another  connection  (p.  412). 

Development  of  the  regional  climax. — The  yellow  birch  may 
be  regarded  as  the  forerunner  of  the  deciduous  trees  which 
characterize  the  regional  climax  forests.  This  tree  is  usually 
represented  in  coniferous  forests  in  the  lowland,  but  there  it 
occupies  a position  of  prominence  only  in  forests  which  are  well 
advanced  in  their  development.  As  the  pioneer  among  the 
deciduous  climax  trees,  it  seems  not  unlikely  that  this  tree, 
together  with  the  red  maple  and  paper  birch,  may  help  to  pave 
the  way  for  the  beech  and  sugar  maple.  The  effect  on  the  moss 
carpet  of  the  periodic  accumulation  of  fallen  leaves  has  been 
referred  to  elsewhere;  and  it  is  at  least  conceivable  that  the 
deciduous  advance-guard  in  the  coniferous  forest,  through  the 
medium  of  leaf-fall,  may  in  some  way  exert  an  ameliorating 
influence  on  the  substratum,  which  facilitates  the  invasion  of  the 
forest  by  beech  and  sugar  maple. 

At  any  rate,  wherever  the  soil  conditions  are  favorable,  conif- 
erous forests  are  superseded  by  forests  of  the  regional  climax 
type.  The  trees  of  the  coniferous  forest  stage  in  the  succession 
may  persist  in  varying  degree,  as  earlier  suggested,  but  they 
relinquish  their  position  of  dominance.  All  stages  of  transition 
may  be  found  between  forests  of  thq  coniferous  type  and  those 
which  are  purely  deciduous.  During  the  transition  from  one 
type  to  another  the  undergrowth  undergoes  various  changes. 
Certain  species  of  the  coniferous  forest  stage,  such  as  Coptis 


3°2 


George  E.  Nichols, 


trifolia  and  Chio genes  hispidula,  vanish  almost  completely ; 
others,  such  as  Pteris  aquilina , Cornns  canadensis,  Epigaea 
repens,  and  Moneses  uniflora,  become  much  less  common;  while 
still  other  species,  such  as  Polystichum  acrostichoides,  Smilacina 
racemosa,  and  Sanicida  marilandica,  which  were  poorly  or  not  at 
all  represented  in  the  coniferous  forest  stage,  come  to  occupy  a 
more  or  less  prominent  position. 


Figure  14. — Granitic  talus  of  the  prevailing  type;  north  of  Cheticamp. 


d.  THE  ASSOCIATION-COMPLEXES  OF  TALUS 

With  reference  to  the  size  of  the  component  rock  fragments 
and  the  consequent  degree  of  stability  of  the  rock  mass,  talus 
slopes  (Fig.  14)  vary  greatly.  Two  extreme  types  may  be  dis- 
tinguished: the  Boulder  Talus  and  the  Gravel  Slide.  Boulder 
talus  consists  essentially  of  large  rock  fragments  (sometimes 
many  feet  in  diameter),  which  tend  to  lodge  together  and  inter- 
lock with  one  another  on  the  slope  in  such  a way  as  to  produce 
a relatively  stable  rock  mass.  A gravel  slide,  on  the  other  hand, 
consists  primarily  of  fine,  loose  rock  debris,  which  is  not  held 
together  in  any  way  but  is  constantly  tending  to  slip  further 


Vegetation  of  Northern  Cape  Breton.  303 

down  the  slope,  and  thus  produces  a very  unstable  rock  mass. 
Between  the  two  extremes  are  all  degrees  of  intergradation. 

The  association-types  of  boulder  talus. — As  in  the  rock  out- 
crop series,  two  types  of  habitat  are  available  to  plants  here,  the 
rock  surfaces  and  the  crannies  between  the  fragments.  The  sur- 
faces of  the  boulders  are  usually  overgrown  with  crustose  and 
foliose  lichens.  Any  of  the  rock  face  species  previously  cited 
may  grow  here.  These,  however,  play  little  or  no  active  part  in 
the  talus  succession  as  a whole : the  latter  is  instituted  almost 
entirely  by  the  plants  which  grow  in  the  crannies.  Here,  through 
the  further  disintegration  of  the  larger  rock  fragments,  and  also 
to  some  extent  from  other  sources,  a soil  accumulates.  Toward 
the  base  of  a talus  slope  soil  gathers  faster  and  soil  moisture 
is  more  abundant  than  higher  up,  so  that  as  a rule  succession 
progresses  much  more  rapidly  here  than  elsewhere  on  the  slope. 
Very  commonly  the  base  of  a talus  slope  will  be  clothed  by  a 
mesophytic  forest  while  above  there  are  only  scattered  trees  and 
shrubs. 

The  shade  and  protection  from  exposure  afforded  by  the  blocks 
which  surround  the  crannies  create  here  conditions  which  are 
congenial  to  mesophytes  as  well  as  to  many  xerophytes.  The 
pioneer  plants  may  include  various  species  of  Cladonia  and  any 
of  the  bryophytes  which  have  been  cited  as  characteristic  of 
crevices  in  the  rock  outcrop  series.  It  also  commonly  includes 
certain  more  mesophytic  species,  such  as  Ptilidium  ciliare, 
Hypnum  Schreberi,  and  Hylocomium  splendens.  The  lichen- 
bryophyte  element  may  perform  an  important  function  in  the 
succession  by  forming  cushions  and  mats  which  often  spread 
away  from  the  crannies  over  the  adjoining  rock  surfaces,  creat- 
ing a substratum  favorable  for  the  germination  of  the  spores 
and  seeds  of  higher  plants.  The  presence  in  the  crannies  of  a 
soil,  however,  permits  the  growth  at  the  outset,  not  only  of 
lichens  and  bryophytes,  but  of  vascular  plants  as  well.  Her- 
baceous plants  are  sparingly  represented  by  Polypodium  vulgare 
and  a few  other  species,  while  the  two  shrubs,  Sambucus  race- 
mosa  and  Rubus  idaeus  canadensis,  usually  occupy  a prominent 
position.  But  both  herbs  and  shrubs  are  subordinate  in  impor- 
tance to  trees.  These  gain  a foothold  early  and  may  predominate 
the  succession  from  start  to  finish.  For  a long  time,  at  least  as 
long  as  the  intermittent  bombardment  of  the  slope  continues  by 


3°4 


George  E.  Nichols, 


rocks  dislodged  from  above,  the  trees  remain  scattered,  and,  at 
this  stage,  paper  birch  commonly  is  the  most  conspicuous  tree. 
The  reason  for  this  frequently  observed  predominance  of  paper 
birch  over  conifers  at  this  time,  as  pointed  out  by  Cooper  (T3, 
pp.  218,  219),  is  undoubtedly  due  to  the  ability  of  the  former  to 
sprout  from  the  stump  and  thereby  recover  from  the  injuries 
inflicted  by  falling  boulders.  Ultimately,  a coniferous  forest  of 
the  type  already  described  may  become  established,  in  which  the 
predominant  trees  include  the  balsam  fir  and  white  spruce, 
the  paper  birch  and  yellow  birch,  the  white  pine,  the  black 
spruce  and  mountain  ash.  On  north-facing  slopes,  coniferous 
forests,  while  attaining  a high  degree  of  mesophytism,  frequently 
represent  the  culminating  phase  of  the  succession : in  other 

words,  they  constitute  an  edaphic  climax.  But,  under  favorable 
conditions,  the  regional  climax  association-type  is  capable  of 
attainment  on  boulder  talus,  as  on  the  glacial  drift. 

The  association-types  of  gravel  slides. — In  extreme  cases,  as, 
for  example,  on  gypsum  slides10  (Fig.  15),  the  instability  of  the 
rock  mass  may  be  so  great  that  plant  life  is  almost  excluded. 
Largely  on  account  of  this  instability,  lichens  and  mosses  usually 
play  but  little  part  in  gravel  slide  successions : only  plants  with 
roots  are  capable  of  maintaining  a foothold  here.  The  most 
important  pioneers  are  xerophytic  ferns  and  seed  plants, 
especially  herbaceous  forms  which  perennate  by  means  of  roots 
and  rhizomes : such  species,  for  example,  as  Pteris  aquilina, 
Dicksonia  punctilobula,  Danthonia  spicata,  Campanula  rotundi- 


10  In  this  connection  it  is  worthy  of  note  that  floristically  the  vegetation 
of  gypsum  outcrops  commonly  differs  to  a marked  degree  from  that  of 
other  rock  outcrops  which  may  be  physically  similar.  On  the  gypsum  the 
vegetation  includes  a pronounced  calciphilous  element  which  elsewhere 
is  mostly  absent.  Prominent  among  the  seed  plants  are  Carex  eburnea, 
Shepherdia  canadensis,  Cornus  circinata,  and  Erigeron  hyssopifolius.  The 
bryophytes  include  Swartsia  inclinata,  Gymnostomum  rupestre,  Tortula 
mucronifolia,  Encalypta  contorta,  Myurella  Careyana,  and  Thuidium 
abietinum.  Generally  speaking,  however,  while  there  are  frequent  other 
evidences  throughout  this  region  of  a similar  correlation  between  the 
chemical  nature  of  the  underlying  rock  and  the  character  of  the  vegetation, 
the  writer  has  been  unable  to  distinguish  any  broad  relationships  of 
general  ecological  significance.  Aside  from  the  influence  of  topography, 
the  general  aspect  of  the  vegetation  appears  to  be  correlated  more  with 
the  physical  character  of  the  substratum  than  with  its  chemical  character. 


Vegetation  of  Northern  Cape  Breton. 


3°5 


folia,  Anaphalis  margaritacea,  and  Solidago  bicolor.  Most  of 
the  weeds  found  in  pastures  and  along  roadsides  thrive  on  gravel 
slides.  Of  the  herbaceous  plants,  the  grasses,  particularly  Dan- 
thonia  spicata,  commonly  play  an  essential  role,  contributing  to 
bring  about  increased  stability  in  the  substratum  through  the 
formation  of  a more  or  less  continuous  sod.  Shrubs,  notably 
Rubus  idaeus  canadensis,  and  trees,  especially  the  white  spruce, 
are  also  important  in  this  respect. 


Figure  15. — Gypsum  (“plaster”)  outcrop  along  shore  of  Ingonish  Har- 
bor. 

Sometimes  a xerophytic  weed  stage  in  the  succession,  in  which 
the  plants  are  scattered  and  the  vegetation  open,  is  followed  by  a 
definite  grass  stage,  in  which  the  ground  is  completely  carpeted 
by  vegetation.  But  more  commonly  trees  are  present  from  the 
outset,  and  the  first  continuous  plant  cover  is  dominated  by  trees, 
which  form  an  open  grove,  the  ground  between  the  trees  being 
grassed  over  or  else  occupied  by  colonial  herbaceous  species,  such 
as  Dicksonia  and  Anaphalis,  or  by  Rubus.  The  white  spruce 
invariably  stands  preeminent  among  the  trees,  but  there  is  a 
scattered  representation  of  balsam  fir,  paper  birch,  balsam  poplar^. 


3°6 


George  E.  Nichols, 


bird  cherry  ( Primus  pennsylvanica) , etc.  In  the  course  of  time 
a closed  coniferous  forest  may  be  developed,  and,  under  favorable 
conditions,  this  may  be  superseded  eventually  by  a forest  of  the 
regional  climax  type. 

One  of  the  commonest  types  of  talus  in  northern  Cape  Breton 
is  shown  in  Fig.  16.  The  rock  fragments  are  relatively  small 
and  the  rock  mass  is  much  less  stable  than  the  large-bouldered 
talus,  though  more  so  than  the  gravel  slide.  The  common 


Figure  16. — Pioneer  association  of  white  spruce,  etc.,  on  granitic  talus; 
Barrasois. 


pioneers  here  are  the  white  spruce,  the  raspberry,  Dicksonia,  and 
Anaphalis. 

2.  The  Formation-types  of  Uplands  along  Streams 

a.  INTRODUCTORY 

In  a general  way,  two  topographic  features  are  intimately 
associated  with  streams : valleys  and  flood  plains.  In  northern 
Cape  Breton  the  valleys  range  from  deep,  narrow  ravines  and 
gorges  in  which  the  stream  occupies  entirely  the  narrow  floor,  on 


Vegetation  of  Northern  Cape  Breton. 


3°7 


the  one  hand,  to  wide,  open  valleys  with  broad,  flat  floor,  on  the 
other.  All  of  the  larger  streams,  in  their  passage  from  the 
interior  toward  the  coast,  flow  during  at  least  part  of  their  course 
through  deep  valleys  (Fig.  17),  while  on  a lesser  scale  ravines 
are  well  developed  along  many  of  the  small  brooks.  In  general, 
so  far  as  the  larger  streams  are  concerned,  narrow  ravines 
(Fig.  19)  are  more  characteristic  of  the  higher,  crystalline  areas, 
broad  valleys  of  the  lower  Carboniferous  regions.  Broad,  open 


Figure  17. — Valley  of  Barrasois  River,  just  above  contact  between 
crystalline  and  Carboniferous  areas ; Pinus  Strobus  in  right  and  left  fore- 
ground. Compare  with  Fig.  18,  photographed  but  a short  distance  down- 
stream. 

valleys  (Figs.  7,  20)  are  especially  well  developed  in  the  zone  of 
contact  between  the  lowland  and  the  highland,  where  very  fre- 
quently the  Carboniferous  lowland  extends  as  a finger-like  depres- 
sion for  several  miles  into  the  heart  of  the  higher  crystalline 
formation.  The  floor  of  such  a valley,  as  a rule,  is  relatively 
flat  and  is  referred  to  locally  as  an  Intervale. 

The  glacial  debris,  which  at  one  time  must  have  buried  the 
floor  of  every  valley  to  a considerable  depth,  has  been  very  largely 


3°8 


George  E.  Nichols, 


scoured  out  from  the  narrow-floored  ravines  through  stream 
activity;  but  in  the  broad-floored  valleys,  as  throughout  the 
Carboniferous  lowland  in  general,  it  may  still  form,  at  least 
locally,  deposits  many  feet  thick.  Wherever  these  heterogeneous 
deposits  are  exposed  to  the  erosive  action  of  the  current,  the 
finer  materials  tend  to  be  carried  away,  the  coarser  constituents 
being  left  behind  and  forming  what  are  here  designated  as 
Boulder  Plains — areas  covered  with  stones,  mostly  rounded,  but 


Figure  18.— Boulder  plain  along  lower  course  of  Barrasois  River. 

of  all  shapes  and  sizes  (Figs.  18,  21).  Where  the  stones  are 
uniformly  small,  they  may  well  be  referred  to  as  Cobble  Plains. 
These  stony  plains  commonly  border  the  larger  streams  wherever 
they  flow  through  deposits  of  glacial  drift.  In  flood  time  they 
are  submerged,  but  ordinarily,  except  for  the  small  channel  per- 
manently occupied  by  the  stream,  they  are  uncovered. 

In  contrast  to  boulder  plains,  which  are  a result  of  degrada- 
tion, flood  plains  are  a product  of  aggradation.  They  are  best 
developed  along  sluggish,  old-age  rivers,  and  at  first  thought 
might  not  be  expected  to  occur  at  all  along  swift,  young  streams, 
like  the  majority  of  those  in  northern  Cape  Breton.  But,  on 


Vegetation  of  Northern  Cape  Breton.  309 

the  contrary,  even  in  narrow  ravines  incipient  flood  plains  may 
be  commonly  observed  in  situations  which  in  some  way  are  pro- 
tected from  the  swift  current  (foreground  in  Fig.  17),  while  in 
wider  valleys  (Fig.  20)  the  stream  is  usually  bordered  by  an 
interrupted  series  of  low,  terrace-like  flood  plains,  which  have 
been  built  up  along  the  less  exposed  banks.  The  flood  plains  of 
rapid  streams,  however,  not  only  in  Cape  Breton,  but  elsewhere  as 
well,  differ  markedly  from  the  familiar  type  of  sluggish  streams. 
There  the  alluvial  deposits  consist  largely  of  fine-grained  sedi- 
ments. Flood  plains  of  this  latter  sort,  in  northern  Cape  Breton, 
have  been  developed  to  a considerable  extent  locally,  particularly 
toward  the  mouths  of  some  of  the  larger  rivers.  Along  rapid 
water  courses,  however,  the  deposits  are  much  coarser,  the  swift- 
ness of  the  current  in  times  of  flood  being  so  great  that  most  of 
the  finer  material  is  washed  away.  Even  where  the  conditions 
for  deposit  are  most  favorable,  the  alluvial  material  along  a 
rapid  stream  is  made  up  largely  of  coarse  sand  and  gravel,  while 
miniature  flood  plains  built  up  almost  wholly  of  cobbles  and 
pebbles  are  frequent  in  less  favorable  situations.  Incidentally, 
it  should  be  remarked  that  while,  in  a sense,  a boulder  plain 
might  be  regarded  as  a flood  plain,  for  obvious  reasons  it  is  best 
treated  separately.  Typical  flood  plains  commonly  overlie 
former  boulder  plains. 

b.  THE  ASSOCIATION-COMPLEXES  OF  ROCK  RAVINES 

This  is  the  only  type  of  ravine  which  need  be  considered.  The 
associations  here  may  be  divided  roughly  into  four  groups,  as 
follows.  (1)  The  stream  bed  association-types:  comprising  the 
vegetation  in  areas  where  the  bottom  is  submerged  at  all  seasons. 
(2)  The  stream  bank  association-types:  comprising  the  vegeta- 
tion of  areas,  mostly  along  the  margin  of  the  stream,  which  are 
flooded  at  times  of  high  water  but  at  other  times,  of  variable 
duration,  are  exposed  to  the  air.  (5)  The  association-types  of 
cliffs : comprising  the  vegetation  of  areas  above  the  flood  zone 
which  are  too  steep  or  unstable  to  support  a forest.  ( 4 ) The 

ravine  forest.  With  reference  to  their  water  relations,  some  of 
these  association-types  are  naturally  classed  under  the  xerarch 
series,  others  under  the  hydrarch  series,  but  this  classification  is 
not  always  easy  to  apply.  In  the  hydrarch  category  should  of 


3 r ° 


George  E.  Nichols, 


course  be  classed  the  stream  bed  association-types,  and  here  also 
it  seems  most  appropriate  to  include  those  stream  bank  and  cliff 
association-types  whose  ecological  aspect  is  obviously  correlated 
with  the  more  or  less  constant  presence  of  an  abundant  water 
supply.  Similarly,  in  the  xerarch  category  should  be  classed  the 
ravine  forest  and  such  of  the  association-types  of  stream  banks 
and  cliffs  as  are  exposed  for  considerable  periods  of  time  to 
more  or  less  xerophytic  conditions.  In  the  present  connection 


Figure  19. — Gorge  along  Indian  Brook;  the  upper  edge  of  the  flood 
zone  is  indicated  by  the  lower  margin  of  the  forest. 

attention  is  directed  primarily  to  ravine  associations  of  the 
xerarch  series.  Apropos,  it  may  be  remarked  that,  for  reasons 
which  the  author  has  pointed  out  elsewhere  (’i6b,  pp.  237,  249, 
250),  in  considering  the  vegetation  of  rock  ravines  from  the 
dynamic  point  of  view,  the  question  of  an  actual  succession  of 
plant  associations,  in  so  far  as  it  is  correlated  with  the  physiogra- 
phic development  of  the  ravine  itself,  may  be  virtually  dis- 
regarded. 

Stream  bank  association-types. — Largely  owing  to  the  narrow- 
ness of  the  channel  to  which  the  rushing  flood  water  ordinarily  is 


Vegetation  of  Northern  Cape  Breton.  31 1 

confined,  the  character  of  the  vegetation  within  the  flood  zone  in 
ravines  is  influenced  to  a marked  degree  by  the  abrading  action 
of  the  current  at  times  of  high  water.  Particularly  is  this  true 
along  the  larger  streams  (Figs.  17,  19),  to  which  the  following 
remarks  primarily  apply.  Woody  plants,  for  the  most  part,  are 
either  absent  or  sparsely  developed  and  even  the  herbaceous 
plants  are  scattered.  The  characteristic  vascular  plants  of  rocky 
banks  between  high  and  low  water  levels  are  herbaceous  peren- 
nials, and  these  are  mostly  restricted  to  crevices  and  similar 
situations  where  their  perennating  roots  and  rhizomes  can  main- 
tain a foothold.  Common  species  are  Equisetum  sylvaticum, 
Deschampsia  flexnosa,  Sagina  procnmbens,  Campanula  rotundi- 
folia,  Erigeron  hyssopifolius,  and  Solidago  bicolor , together  with 
various  weeds,  such  as  Prunella  vulgaris,  Achillea  Millefolium, 
and  Chrysanthemum  Leucantliemum.  In  addition  to  these,  a 
prominent  position  is  frequently  occupied  by  various  bryophytes, 
such  species  as  Preissia  quadrata,  Fossombronia  foveolata, 
Marsupella  emarginata,  Nardia  obovata,  Hygrobiella  laxifolia, 
Grimmia  apocarpa,  G.  conferta,  and  Racomitrium  aciculare. 
Toward  the  upper  margin  of  the  flood  zone,  skirting  the  lower 
edge  of  the  ravine  forest,  there  is  commonly  a narrow  fringe  of 
shrubs  which  constitutes  a more  or  less  distinct  association-type. 
•The  characteristic  species  here  is  Alnus  mollis,  with  which  may 
be  associated  Salix  humilis,  Rubus  pubescens,  Acer  spicatum, 
Diervilla  Lonicera,  and  other  shrubs,  together  with  such  herba- 
ceous mesophytes  as  Osmunda  Claytoniana,  Phegopteris  poly- 
podioides,  Streptopus  amplexifolius,  and  Solidago  latifolia. 

Conditions  similar  to  those  just  outlined  may  prevail  in  ravines 
along  small  streams,  but  here  the  stream  bank  vegetation  com- 
monly is  such  that  it  has  seemed  best  to  treat  it  under  the 
hydrarch  series  (see  p.  368). 

Cliff  association-types. — Certain  pteridophytes  are  especially 
characteristic  of  crevices  in  cliffs,  well  above  the  level  of  the 
stream,  notably  Polypodium  vulgare,  Aspidium  fragrans,  Cysto- 
pteris  fragilis,  Woodsia  ilvensis,  and  Lycopodium  Selago.  With 
the  exception  of  perhaps  the  last-named  species,  these  grow  best 
in  moist,  somewhat  shaded  habitats.  Various  of  the  herbaceous 
perennials  of  the  flood  zone  are  equally  common  here,  particularly 
Deschampsia  and  Campanula,  while  the  crevice  plants  mentioned 
earlier  in  connection  with  the  rock  outcrop  series  of  ordinary 


3 1 2 


George  E.  Nichols, 


uplands  may  likewise  be  well  represented.  Of  special  interest* 
however,  is  the  conspicuous  position  commonly  occupied  by  the 
mosses  and  liverworts,  which,  in  favorable  situations,  may 
develop  luxuriantly,  growing  either  in  crevices  or  on  sloping  or 
perpendicular  rock  surfaces.  Representative  species  are  listed 
below,  and,  in  addition  to  these,  various  of  the  species  of  wet 
cliffs  (p.  370)  may  grow  here. 


Bazzania  tricrenata 
Diplophyllum  taxifolium 
Porella  platyphylloidea 
Radula  complanata 
Lejeunea  cavifolia 
Andreaea  petrophila 
Swartzia  montana 
Fissidens  osmundoides 


Tortella  tortuosa 
Racomitrium  fasciculare 
Ulota  americana 
Pohlia  cruda 
Bartramia  pomiformis 
Hedwigia  albicans 
Drepanocladus  aduncns 
Polytricham  alpinum 


The  ravine  forest. — Nowhere  in  the  lowland  of  northern  Cape 
Breton  are  forests  of  the  coniferous  type  more  luxuriantly 
developed  than  in  ravines.  In  general,  these  forests  conform 
closely  with  the  regional  climax  type  of  the  mountains,  and 
need  not  be  described  in  detail  at  this  point.  Such  forests  here 
represent  an  edaphic  climax  association-type,  and  as  such  their 
development  is  correlated  very  largely  with  local  peculiarities  of 
temperature  and  soil  moisture.  They  are  best  developed  on 
north-facing  slopes,  where  the  failure  of  the  succession  to  pro- 
ceed beyond  the  coniferous  forest  stage  may  be  attributed  to  the 
slowness  with  which  the  snow  melts  and  the  ground  thaws  out  in 
spring  and  to  the  relatively  low  temperatures  which  obtain 
throughout  the  season.  Quite  commonly  the  north-facing  slope 
of  a ravine  supports  a coniferous  forest  while  the  opposite,  south- 
facing slope  is  clad  with  a forest  of  the  regional  climax  type. 
On  north-facing  slopes,  coniferous  climax  forests  are  by  no 
means  confined  to  ravines : one  of  the  most  distinctly  boreal 
examples  of  upland  forest  which  has  come  to  the  writer’s  atten- 
tion in  the  lowland  is  situated  along  the  lower  slopes  of  a steep 
mountain  side,  where  ice  frequently  lingers  as  late  as  August, 
notwithstanding  the  fact  that  it  faces  an  open  intervale  which 
was  formerly  occupied  by  a deciduous  forest.  In  ravines  which 


Vegetation  of  Northern  Cape  Breton.  313 

run  north-and-south,  and  where  both  flanks  are  thus  equally  well 
exposed  to  the  sun,  on  the  other  hand,  the  ravine  forest  may  be 
wholly  of  the  deciduous  type. 

One  feature  of  coniferous  ravine  forests  worthy  of  special 
mention  is  their  great  mesophytism,  as  evinced  more  particularly 
by  the  wonderful  development  of  the  bryophytic  ground  cover. 
Commonly  the  ground  beneath  the  trees  is  literally  buried  beneath 
a thick  bed  of  liverworts  and  mosses.  The  sphagnums  in 
particular— such  species  as  Sphagnum  capillaceum  tenellum,  S. 
Girgensohnii,  S.  quinquefarium,  and  S.  subsecundum — commonly 
form  wide,  deep  cushions,  flourishing  here  as  in  no  other  upland 
habitat  in  this  region. 

The  summer  evaporating  power  of  the  air  in  coniferous  ravine 
forests,  as  compared  with  other  habitats. — During  the  summer 
of  1915  a series  of  porous  cup  atmometers  was  operated,  for  a 
period  of  a little  more  than  two  weeks,  in  various  habitats,  with 
the  object,  primarily,  of  ascertaining  the  relative  evaporating 
power  of  the  air  in  coniferous  ravine  forests  as  compared  with  the 
deciduous  climax  forests.  The  habitats  selected  were  as 
follows : 

Station  1 (“Open — Shore”)  : Open  hillside,  east  exposure, 
half  a mile  from  seacoast. 

Station  2 (“Open — Intervale”)  : Open  hillside,  east  exposure, 
four  miles  from  coast  at  head  of  intervale. 

Stations  j and  4 (“Hardwood”)  : Hardwood  (climax)  virgin 
forest ; east  exposure  ; near  station  2. 

Station  5 (“Ravine  Conifer — -High”):  Coniferous  forest; 

steep  north-facing  slope  of  ravine,  about  250  feet  above  river ; 
near  station  1. 

Station  6 (“Ravine  Conifer — Low”)  : Dense  coniferous  forest; 
steep  north-facing  slope  of  ravine,  about  150  feet  above  river; 
near  station  1. 

Station  7 (“Ravine — Bed”)  : Gravel  bar  in  bed  of  stream  ; 
exposed  to  sun  about  six  hours  daily ; stream  bed  about  75  feet 
wide  at  this  point ; near  station  1. 

The  readings  obtained  are  given  in  Table  VI.  During  much 
of  the  period  that  the  cups  were  in  operation  the  weather  was 
intermittently  rainy,  foggy,  and  clear.  From  August  3 to 
August  7,  however,  it  was  uninterruptedly  clear,  so  that  for  pur- 


31  4 


George  E.  Nichols, 


TABLE  VI 

Rate  of  Evaporation  in  Various  Habitats,  as  Indicated  by  the  Porous 

Cup  Atmometer 


July  22- 
July  27 

July  27- 
August  3 

August  3- 
August  7 

Total 

Station  1:  Open — shore 

28.8  cc. 

45.0  CC. 

84.2  CC. 

158.0  cc. 

Station  2:  Open — intervale 

39-4  cc. 

53.3  cc. 

91.9  CC. 

184.6  cc. 

Station  3:  Hardwood  A 

16.0  cc. 

19.6  cc. 

42.1  cc. 

77.7  cc. 

Station  4:  Hardwood  B 

15.3  cc. 

16.3  cc. 

37.8  cc. 

69.4  cc. 

Station  3:  Ravine  Conifer — high..  . . 

14.4  cc. 

20.6  cc. 

52.5  cc. 

87.5  cc. 

Station  6:  Ravine  Conifer — low.  . . . 

II. 0 cc. 

14.0  cc. 

43.3  cc. 

68.3  cc. 

Station  7:  Ravine — bed 

24.1  cc. 

31. 1 cc. 

63.0  cc. 

118.2  cc. 

pose  of  comparison  the  third  column  of  figures  is  the  most 
reliable.  From  an  examination  of  these  figures  various  facts 
are  obvious,  but  only  one  of  these  need  be  emphasized,  namely, 
that  the  evaporating  power  of  the  air  in  the  coniferous  ravine 
forest  differs  little  from  that  in  the  climax  deciduous  forest. 
Greater  humidity,  then,  will  not  explain  the  luxuriant  develop- 
ment of  the  moss  carpet  in  a ravine  forest.  Other  explanations 
have  already  been  suggested. 


C.  THE  ASSOCIATION-COMPLEXES  OF  OPEN  VALLEYS 

Chiefly  by  reason  of  the  protection  which  they  afford  from 
cold  winds  in  spring  and  fall,  open  valleys  (Fig.  20),  in  general, 
present  edaphic  conditions  which  are  more  congenial  to  plants 
of  southward  distribution  than  those  of  any  other  type  of  habitat- 
complex.  Robinson  (’03)  has  already  called  attention  to  the 
relative  abundance  in  the  intervales  of  eastern  Nova  Scotia  of 
early  spring-flowering  plants,  and  the  writer  (i6b,  pp.  252,  253) 
has  commented  on  parallel  conditions  in  Connecticut.  Nowhere 
in  northern  Cape  Breton  are  forests  of  the  deciduous-hemlock 
climax  type  more  luxuriantly  developed  than  on  the  floors  of 
broad,  sunny  valleys,  i.  e.,  in  the  intervales.  Here,  more 
abundantly  than  anywhere  else,  grow  the  hemlock,  red  oak.  white 
ash,  and  elm  ( Ulmus  americana) , among  the  trees,  together  with 
various  herbaceous  plants  of  pronounced  southward  range.  Of 
the  latter,  many  forms,  such  as  Anemone  virginiana,  Sangui- 
naria  canadensis,  and  Dicentra  Cucullaria  ( fide  Robinson  ’03), 
Actaea  alba,  Epifagus  virginiana,  and  Triosteum  aurantiacum , 


Vegetation  of  Northern  Cape  Breton.  315 

are  practically  restricted  to  the  intervales  or  to  the  adjoining 
slopes.  From  the  standpoint  of  their  physiographic  origin,  the 
intervales  are  largely  the  result  of  stream  activity,  and  their 
vegetation  in  part  is  that  of  the  boulder  plains  and  flood  plains 
which  are  still  in  the  course  of  formation.  But  in  large  part,  so 
far  as  the  vegetation  is  concerned,  the  influence  of  the  stream 
is  of  merely  historical  significance.  In  the  case  of  boulder  plains 
and  flood  plains,  local  soil  as  well  as  local  atmospheric  factors 
have  to  be  taken  into  account. 


Figure  20. — The  Big  Intervale  along  North  Aspy  River : floor  of  valley 
at  this  point  largely  under  cultivation ; in  background,  talus  slopes  in 
various  stages  of  forestation ; view  taken  toward  upper  end  of  intervale ; 
compare  Fig.  7. 

d.  THE  ASSOCIATION-COMPLEXES  OF  BOULDER  PLAINS 

In  extreme  cases,  vegetation  may  be  almost  wholly  lacking  on 
boulder  plains  (Fig.  18).  But  such  cases  are  not  common.  While 
from  a distance  the  lower  and  more  frequently  flooded  portions  of 
a boulder  plain  may  have  almost  the  aspect  of  a desert,  closer 
inspection  usually  reveals,  even  here,  a goodly  representation  of 
shrubs  and  herbaceous  plants,  which  maintain  a precarious  foot- 


316 


George  E.  Nichols, 


hold  in  the  interstices  between  the  cobbles  and  boulders,  rooting  in 
the  sand  and  gravel  which  have  accumulated  in  the  shelter  afforded 
by  the  larger  rocks.  The  pioneers  are  preeminently  herbaceous 
perennials : species  which  are  able  to  tide  over  the  unfavorable 
periods  by  means  of  underground  organs.  Except  for  shrubby 
willows  (such  species  as  Salix  cor  data,  S.  lucida,  and  5. 
Immilis),  which  are  able  to  survive  considerable  battering  and 


Figure  21. — -View  along  Middle  River,  showing  boulder  plain  with 
scrubby  willows,  etc.  (left  foreground),  young  flood  plain  with  pioneer 
tree  stage  (center,  mid-distance),  and  mature  flood  plain,  now  under 
cultivation  (right,  mid-distance). 

locally  may  form  dense,  low  thickets  (Fig.  21),  woody  plants  are 
scarce. 

On  the  higher  parts  of  a boulder  plain,  the  vegetation  is  much 
more  abundant,  but  always  open.  In  addition  to  the  willows, 
species  of  alder,  particularly  Alnus  incana,  are  ordinarily 
conspicuous  here,  together  with  such  other  woody  plants  as 
Rubus  idaeus  canadensis,  R.  pnbescens,  and  Spiraea  latifolia.  A 
list  of  some  of  the  more  characteristic  herbaceous  plants  of 
boulder  plains  is  given  below.  This  list  does  not  include  weeds, 
many  of  which  occupy  a very  prominent  position  here. 


Vegetation  of  Northern  Cape  Breton. 


3i7 


Equisetum  arvense 


Viola  pallens 
Epilobium  angustifolium 
Epilobium  adenocaulon 
Apocynum  cannabinum 
Eupatorium  purpurenm 
Solid  ago  canadensis 
Aster  radula 
Aster  puniceus 


Calamagrostis  canadensis 


Agropyron  repens 
Poa  pratensis 


Carex  torta 


Ranunculus  repens 
Fragaria  virginiana 
Viola  cucullata 


e.  THE  ASSOCIATION-COMPLEXES  OF  FLOOD  PLAINS 

Transition  from  boulder  plain  to  flood  plain. — It  commonly 
happens,  sooner  or  later,  that  the  stream  shifts  its  course  or  that 
the  current  is  deflected  by  some  sort  of  an  obstruction,  so  that  an 
area  occupied  by  a boulder  plain  becomes  protected  in  a measure 
from  the  erosive  activity  of  the  stream.  If  the  protection  is 
sufficient,  degradation  may  become  largely  superseded  by 
aggradation,  and  a flood  plain  may  gradually  be  built  up  on  top 
of  the  former  boulder  plain  (Fig.  21).  Eventually,  even  along 
swift  stretches  of  the  stream,  such  flood  plains  may  attain  a 
height  of  five  or  six  feet  above  low  water  level.  At  first  com- 
posed of  coarse  gravel  and  cobbles,  as  the  surface  is  raised 
higher  the  successive  deposits  become  finer,  and  finally  the  soil 
comes  to  consist  of  coarse  sand.  Only  in  exceptionally  favorable 
situations,  however,  does  the  soil  approximate  the  fine  alluvium 
of  old-age  rivers. 

The  succession  of  plant  associations  outlined. — In  the  familiar 
type  of  flood-plain  succession  (to  be  discussed  later),  the  pioneer 
stages  of  the  series  are  usually  hydrophytic : in  other  words,  the 
succession  is  hydrarch.  In  the  boulder  plain-flood  plain  succes- 
sion, on  the  other  hand,  the  pioneer  stages,  as  a rule,  are  relatively 
xerophytic : that  is,  the  succession  is  xerarch.  Three  more  or 
less  distinct  stages  in  the  succession  may  be  distinguished : the 
gravel  bar  stage,  the  pioneer  tree  stage,  and  the  edaphic  climax 
forest. 

The  gravel  bar  association-type. — The  pioneer  association-type 
of  gravel  bars  consists  largely  of  the  shrubs  and  herbaceous 
perennials  listed  as  characteristic  of  boulder  plains,  most  of  which 
grow  in  greater  profusion  here  than  there.  It  also  may  include 
many  species  which  are  not  prominent  on  boulder  plains : such, 
for  example,  as  Alnus  mollis  and  Diervilla  Lonicera;  Campanula 


George  E.  Nichols, 


3>« 

rotundifolia,  Anaphalis  margaritacea,  and  Centaurea  nigra.  The 
mosses,  Racomitrium  canescens  and  Polytrichum  piliferum,  fre- 
quently form  a loose,  discontinuous  ground  cover  in  protected 
spots ; while  species  of  Cladonia  may  also  be  present.  Locally, 
wherever  the  soil  is  fairly  moist,  the  early  vegetation  may  include 
mesophytic  species,  such  as  Clematis  virginiana,  Thalictrum  poly- 
gamum,  and  Heracleum  lanatum — forerunners  of  subsequent 
stages  in  the  succession. 

The  pioneer  tree  association-type. — Although  the  vegetation 
in  the  gravel  bar  stage  of  the  succession  is  predominated  by 
shrubby  and  herbaceous  species,  trees  may  be  present  from  the 
outset.  The  balsam  poplar,  more  than  any  other  species,  is 
preeminently  the  distinctive  pioneer  tree  of  gravelly  or  sandy 
flood  plains,  although  it  often  shares  this  honor  with  the  paper 
birch  and  white  spruce  (Fig.  21).  The  balsam  poplar  owes  its 
prominence  to  its  copious  root  system  and  exceptional  ability  to 
maintain  itself  on  shifting  alluvial  soils,  its  tendency  to  repro- 
duce and  spread  by  means  of  root  suckers,  and  its  rapid  rate  of 
growth,  which  enables  it  to  outstrip  any  chance  competitors.  In 
these  respects  it  resembles  its  southern  relative,  the  cottonwood 
( Populus  deltoides) , of  which  it  may  be  regarded  as  an  ecological 
counterpart.  One  frequently  encounters  on  flood  plains  groves 
of  good-sized  balsam  poplars,  beneath  which  the  more  character- 
istic trees  of  the  climax  forest  apparently  are  just  beginning  to 
establish  themselves.  But  any  of  the  climax  trees  may  appear 
simultaneously  with  the  poplar.  On  one  small,  treeless  stretch 
of  gravelly  flood  plain,  for  example,  the  writer  noted  seedlings 
of  nearly  every  tree  (all  except  white  pine,  hemlock,  and  red 
oak),  which  has  been  cited  earlier  as  growing  in  the  climax 
forest;  also  seedlings  of  bird  cherry  and  choke  cherry  ( Prunus 
virginiana) . For  the  reasons  suggested  above,  however,  the 

poplar  usually  gains  a temporary  ascendancy  over  its  competitors, 
thereby  giving  rise  to  a more  or  less  distinct  phase  in  the  succes- 
sion. 

The  edaphic  climax  forest. — Flood  plain  forests  of  the  sort 
ordinarily  associated  with  old-age  rivers  have  been  developed 
along  some  of  the  larger  lowland  streams,  and  in  some  cases  the 
physiographic  history  of  the  areas  which  these  occupy  has 
probably  been  similar  to  that  of  flood  plains  as  described  in  the. 
preceding  paragraphs.  But  in  the  most  typical  instances 


Vegetation  of  Northern  Cape  Breton. 


3 1 9 


observed,  such  forests  represent  the  culmination  of  hydrarch 
rather  than  xerarch  successional  series,  and  they  will  therefore 
be  discussed  later  (p.  371),  in  connection  with  hydrarch  succes- 
sions. 

The  average  climax  forest  of  sandy  flood  plains  along  swift 
streams  approximates  closely  the  climatic  climax  forest-type  of 
the  region,  differing  from  this  chiefly  in  the  presence,  or  more 
luxuriant  development,  of  such  species  as  Ulmus  americana  and 
Fraximts  americana , among  the  trees,  and  of  various  herbaceous 
plants,  such  as  the  following: 


Osmunda  Claytoniana 
Polystichum  Braunii 
Cinna  latifolia 
T rillium  cernuum 
Smilacina  racemosa 
List  era  convallarioides 


Streptopus  amplexifolius 
Thalictrum  polygamum 
Sanicula  marilandica 
0 smorhiza  divaricata 
Pyrola  asarifolia 
Solidago  latifolia 


3.  The  Formation-types  of  Uplands  along  the  Seacoast 

a.  INTRODUCTORY 

Under  this  heading  are  included  only  those  upland  associations 
which  are  peculiar  to  habitats  in  the  immediate  proximity  of  the 
shore  and  whose  ecological  aspect  is  obviously  correlated  with 
this  fact.  The  character  of  vegetation  along  the  seacoast  is 
influenced  to  a greater  or  less  degree  by  wind,  salt  water,  and 
physiographic  agencies.  The  plant  associations  are  best  classi- 
fied with  reference  to  physiographic  factors,  as  (/)  Associations 
along  Eroding  Shores,  and  (2)  Associations  along  Depositing 
Shores.  As  eroding  shores  are  classed  the  sea  bluffs  and  head- 
lands which  form  such  a striking  topographic  feature  along  much 
of  the  coastline.  Depositing  shores  include  the  commonly 
encountered  shingle  beaches  and  the  less  frequently  encountered 
sandy  beaches  and  dunes. 

In  addition  to  the  figures  that  accompany  the  description  which 
follows,  attention  may  be  called  in  this  connection  to  Figs.  3,  6, 
8,  15,  33,  38,  41. 

h.  THE  ASSOCIATION-COMPLEXES  OF  SEA  BLUFFS  AND  HEADLANDS 

Association-types  of  rocky  sea  bluffs. — -The  application  of  the 
term  sea  bluff  is  here  restricted  to  the  more  or  less  precipitous 


320 


George  E.  Nichols, 


slopes  which  face  directly  on  the  shore  and  therefore  are  most 
exposed  to  the  action  of  waves  and  spray  (Fig.  3).  Along  such 
bluffs  there  is  usually  a pronounced  zonational  arrangement  of 
plant  associations.  Between  low  and  high  tide  levels,  wherever 
the  base  of  the  bluffs  is  submerged,  the  rocks  are  usually  plastered 
with  sea-weeds,  prominent  among  which  are  species  of  Fuchs 
and  Ascophyllum.  Above  high  tide  level  is  a zone  of  varying 
width  in  which,  owing  largely  to  the  mechanical  action  of  waves 


Figure  22. — Juniperus  horisontalis  on  sea  bluff ; Middle  Head,  Ingonish. 

and  ice,  vegetation  is  absent.  Higher  up,  and  sometimes  reach- 
ing to  a height  of  thirty-five  or  forty  feet,  is  a zone  in  which 
the  vegetation  consists  largely  of  scattered  halophytic  crevice  ) 
plants.  The  upper  limits  of  this  zone  are  presumably  determined 
by  the  height  of  the  waves  in  winter  storms.  The  most  abundant 
plant  here  is  Plantago  decipiens,  along  with  which  commonly 
grow  Solidago  sempervirens  and  Sagina  procumbens — the  latter, 
of  course,  hardly  to  be  considered  a typical  halophyte.  Other 
halophytic  species  which  may  inhabit  crevices  or  ledges  toward 
the  upper  edge  of  this  zone  and  which,  like  the  preceding',  may 
also  occur  on  low  headlands  far  beyond  the  actual  reach  of  the 
waves,  are  Potentilla  pacifica,  Atriplex  patula  liastata,  and 
Lathyrus  maritimus.  The  most  characteristic  plant  on  that  part  j 


Vegetation  of  Northern  Cape  Breton. 


32f 


of  a bluff  which  lies  beyond  the  usual  reach  of  the  waves  is  the 
trailing  juniper  ( Junip  eras  horizontalis) , which  commonly 
sprawls  out  here  in  great  profusion  (Fig.  22),  and  is  only  occa- 
sionally found  in  any  other  habitat.  Commonly  associated  with 
this  shrub  is  the  crowberry  ( Empetrum  nigrum ) and  frequently 
the  low  juniper  ( Juniperus  communis  depressa),  while  any  of  the 
other  species  to  be  cited  presently  as  occurring  on  headlands  may 
also  grow  in  the  crevices  of  precipitous,  rocky  sea  bluffs. 


Figure  23. — Alnus  mollis  and  Picea  canadensis  on  sea  bluff  of  clayey 
drift;  Cape  North. 

Association-types  of  sea  bluffs  in  uncompacted  rock. — So  long 
as  a sea  bluff  of  clay  or  glacial  drift  continues  to  be  acted  on, 
from  time  to  time,  by  the  waves,  vegetation  is  scantily  developed. 
Just  as  along  the  shores  of  the  Great  Lakes  (see  Cowles  ’01,  pp. 
164-167),  about  the  only  plants  present  here  are  xerophytic 
annuals  and  “slump  plants”  (i.  e.,  plants  which  have  slid  down 
from  the  crest  of  the  bluff).  As  soon,  however,  as  there  is  a 
cessation  or  diminution  in  the  erosive  activity  of  the  waves, 
which  may  be  brought  about  by  the  formation  of  a shingle  beach 
between  the  bluff  and  the  sea  or  through  the  accumulation  along 
the  base  of  the  bluff  of  boulders  derived  by  erosion  from  the 


322 


George  E.  Nichols, 


bluff  itself,  a plant  cover  is  rapidly  developed.  Equisetum 
arvense  and  Agrostis  alba  maritima  frequently,  and  Elymus 
arenarius  occasionally  are  conspicuous  pioneers,  but  for  the  most 
part  the  pioneer  species  here  are  largely  weeds  and  slump  plants. 
Sometimes  a grassy  sod  is  formed,  but  more  commonly  Alnus 
mollis  (Fig.  23)  comes  in  along  with  the  grasses  and  forms 
a dense  thicket.  Sooner  or  later,  trees  appear,  mostly  white 
spruce  and  paper  birch,  and  these  may  supersede  the  alders, 
forming  a low,  scrubby  forest  along  the  bluff.  The  trees  often 
exhibit  the  same  one-sided  habit  as  those  on  headlands. 


Figure  24. — Exposed  rocky  headland  at  White  Point ; scrubby  forests, 
mostly  white  spruce ; in  right  foreground  a characteristically  one-sided 
spruce.  Photograph  by  Dr.  L.  H.  Harvey. 


Owing  to  the  abundance  of  seepage  water,  soil  conditions 
locally,  especially  along  clay  bluffs,  may  be  unusually  favorable 
for  plants,  and  in  such  places  it  is  a common  thing  to  find  the 
vegetation  made  up  in  large  part  of  species  which  are  ordinarily 
associated  with  swamps  or  flood  plains : such,  for  example,  as 
Alnus  incana,  Calamagrostis  canadensis,  Juncus  effusus  and 
various  sedges,  Heracleum  lanatum,  Eupatorum  purpureum,  and 
Aster  puniceus.  Associations  of  this  sort,  though  mentioned 
here  for  convenience,  should  naturally  be  classed  under  the 
hydrarch  series. 

Association-types  of  exposed  headlands. — Bleak  headlands  like 
the  one  pictured  in  Fig.  24  are  a prominent  feature  of  the  coast, 


Vegetation  of  Northern  Cape  Breton.  323 

especially  northward.  In  the  vicinity  of  Cape  North  and  in 
other  very  exposed  situations  the  mountain  sides  in  some  places 
are  devoid  of  forest  from  sea  level  to  a height  of  fully  a thousand 
feet.  Without  doubt  many  of  these  areas  were  formerly  wooded 
and  their  barren  aspect  has  been  induced  primarily  through  the 
action  of  fire  or  human  activity;  but  the  continuance  of  this 
condition  is  attributable  very  largely  to  the  retarding  effect  on 
succession  of  exposure  to  strong  winds,  frequently  laden  with 


Figure  25. — Detail  view  of  vegetation  on  exposed  headland  shown  in 
Fig.  24;  see  text.  Photograph  by  Dr.  L.  H.  Harvey. 


salt  spray.  Wherever,  on  headlands  of  the  sort  pictured,  there 
is  a depression  which  affords  shelter,  scrubby  forests  are 
encountered,  while  scattered  trees  are  commonly  present  in  the 
barren  area  itself.  These  latter,  as  well  as  many  of  the  trees 
which  fringe  the  lower  margin  of  the  forest  farther  up  the  slope, 
are  usually  unsymmetrical  in  shape  and  dwarfed  in  size.  Fre- 
quently the  living  part  of  the  crown  is  wholly  on  the  landward 
side  of  the  tree. 

In  some  cases  the  predominant  type  of  vegetation  on  these 
headlands  is  grass : species  such  as  Danthonia  spicata,  Festnca 
rubra,  and  Deschampsia  flexuosa.  But  more  often  (Fig.  25) 


324 


George  E.  Nichols, 


the  ground  is  covered  very  largely  with  a dense  tangle  of  low, 
sprawling  shrubs  which  are  seldom  more  than  a foot  high. 
Perhaps  the  most  characteristic,  and  commonly  the  predominant 
shrub  is  the  crowberry,  but  associated  with  this  and  often  equally 
abundant  may  be  Juniperus  communis  depressa,  Vaccinium 
Vitis-Idaea,  V.  pennsylvanicum , and  occasionally  Juniperus  hori- 
zontalis.  Other  species  commonly  encountered  on  bleak,  exposed 
headlands,  but  not  yet  mentioned  in  this  connection,  are  listed 
below. 

Botrychium  ramosum 
Smilacina  stellata 
Iris  setosa  canadensis 
Myrica  carolinensis 
Arenaria  lateriflora 
Fragaria  virginiana 
Potentilla  tridentata 
Lathyrus  palustris 
Ligusticum  scothicum 

To  these  should  be  added  Cladonia  sp.,  Polytrichum  piliferum, 
and  Polytrichum  juniperinum,  which  frequently  carpet  the  bare 
soil  where  other  vegetation  is  absent. 

C.  THE  ASSOCIATION-COMPLEXES  OF  BEACHES  AND  DUNES 

Association-types  of  shingle  beaches. — Even  along  parts  of  the 
coast  which  are  exposed  to  active  erosion,  at  least  where  the 
eroding  land  mass  consists  of  glacial  drift,  a rocky,  beach-like 
strip  commonly  intervenes  between  the  foot  of  the  bluff  and  the 
water’s  edge.  Such  deposits  may  be  composed  in  part  of  wave- 
washed  material,  but  as  a rule  they  are  largely  made  up  of 
boulders  and  cobbles  of  all  sizes  which  have  been  washed  out  of 
the  bluff  itself.  The  analogy  with  the  boulder  plain  is  obvious. 
All  degrees  of  transition  exist  between  such  deposits,  which  may 
be  virtually  destitute  of  vegetation,  and  the  typical  shingle 
beaches,  which  constitute  a familiar  feature  along  the  shore. 
These  latter  commonly  form  a narrow  fringe  along  the  seaward 
edge  of  the  land,  but  wherever  there  are  reentrants  in  the  coast 
line,  barriers  and  spits  tend  to  be  developed.  St.  Ann’s  Bay  and 
Ingonish  Harbor  are  nearly  closed  in  by  narrow,  rocky  spits. 


Cornus  canadensis 
Gaultheria  procumbens 
Halenia  deflexa 
Euphrasia  Randii 
Euphrasia  Randii  Farlowii 
Campanula  rotundifolia 
Solidago  puberuta 
Aster  novi-belgii 


Vegetation  of  Northern  Cape  Breton.  325 

and  there  are  similar  spits  at  the  mouth  of  the  Barrasois  River 
and  Indian  Brook.  Near  the  Barrasois  and  at  South  Bay, 
Ingonish  (Fig.  42),  lakes  of  considerable  size  have  been  cut  off 
from  the  sea  by  barriers,  the  one  at  the  latter  place  being  fresh 
and  several  feet  higher  than  high  tide  level.  Small  ponds  and 
lagoons,  cut  off  by  barriers,  are  of  frequent  occurrence  (Fig.  26). 

In  a general  way,  a shingle  beach,  like  a sandy  beach,  is  sub- 
divided into  three  more  or  less  distinct  zones  which,  following  the 
classification  of  Cowles  (’oi,  p.  170),  may  be  termed  respectively 
the  lower,  middle,  and  upper  beaches  (Fig.  27).  The  lower 


Figure  26. — Shingle  beach  enclosing  small  fresh  pond ; scrubby  spruces, 
etc.  in  foreground,  habit  largely  the  result  of  grazing;  in  background, 
second  growth  spruce,  etc.;  Wreck  Cove.  Photograph  by  Dr.  L.  H. 
Harvey. 

beach  is  the  part  submerged  by  ordinary  high  tides.  It  ranges  in 
width  from  a few  yards  to  more  than  a hundred  feet.  The 
deposit  here  (at  least  in  summer)  is  usually  gravelly  or  sandy 
toward  its  lower  limit,  becoming  pebbly  above  and  gradually 
merging  with  the  shingle.  Except  for  the  occasional  presence 
near  low  tide  level  of  Zostera  marina  and  brown  algae  such  as 
Fncus,  vegetation  is  absent.  The  middle  beach  comprises  that 
part  of  the  beach  immediately  above  the  lower  beach  which  is 
swept  by  the  waves  of  winter  storms  or  is  covered  over  by  ice 
in  winter.  Like  the  lower  beach,  it  varies  greatly  in  width.  The 
deposit  here  consists  almost  wholly  of  water-rounded  cobbles 


326 


George  E.  Nichols, 


and  pebbles,  ranging  from  the  size  of  hens’  eggs  up  to  six  inches 
or  more  in  diameter — the  type  of  accumulation  commonly 
referred  to  as  Shingle.  Vegetation  is  sparse  and  xerophytic, 
practically  the  only  plants  ordinarily  present  being  the  annual, 
Cakile  edentula,  and  the  herbaceous  perennials,  Lathyrus 
maritimus  and  Mertensia  maritima.  The  last-named  species,  the 
so-called  sea  lungwort,  with  its  glaucous  foliage  and  rose-pink  or 
blue  flowers,  and  growing  in  depressed,  circular  patches  two  or 


Figure  27. — Shingle  beach  near  mouth  of  Barrasois  River;  forest  of 
white  spruce,  etc.  along  landward  edge. 


three  feet  in  diameter,  is  by  far  the  most  striking  of  the  beach 
plants.  The  upper  beach  includes  that  part  of  the  beach  which, 
except  during  unusual  storms,  when  parts  or  all  of  it  may  be 
wave  swept,  lies  beyond  the  reach  of  the  waves  at  all  seasons  of 
the  year.  Its  crest  is  commonly  more  than  three  and  occasionally 
as  much  as  six  or  eight  feet  higher  than  ordinary  high  tide  level. 
Stones  are  cast  up  on  these  higher  beaches  only  by  exceptionally 
severe  storms,  perhaps  years  apart.  Like  the  middle  beach,  the 
upper  beach,  especially  in  its  more  exposed  parts,  may  be  little 
more  than  a great  stone  heap  on  which,  except  for  a frequently 


Vegetation  of  Northern  Cape  Breton.  327 

luxuriant  growth  of  lithophytic  lichens,  vegetation  is  scantily 
developed.  Common  lichens  on  the  shingle  are  Rhizocarpon 
geographicum  (crustose),  a form  which  is  very  conspicuous  by 
reason  of  its  bright,  greenish  yellow  color,  and  Lecidea  tenc- 
brosa  Flot.  (crustose)  and  Gyrophora  liyperborea  (foliose),  both 
of  which  are  blackish  in  color.  As  a rule,  however,  even  in  such 
places,  there  is  more  or  less  gravel  and  coarse  sand  underneath 
the  stony  surface  layer,  while  in  the  older  parts  of  the  upper 
beach  the  shingle  in  some  cases  (Fig.  28)  has  been  covered  over 


Figure  28. — Spit  near  mouth  of  Barrasois  River;  to  right,  a typical 
shingle  beach ; to  left,  a mixture  of  sand  and  shingle,  overgrown  with 
Ammophila,  white  spruce,  etc. 


by  sand  to  such  an  extent  as  to  produce  conditions  approximat- 
ing those  to  be  described  presently  as  characteristic  of  sandy 
beaches.  All  intergradations  may  be  found  on  lea  slopes  between 
rocky  shingle  at  one  extreme  and  sandy  beach  at  the  other. 

On  the  upper  beach,  soil  conditions  usually  favor  the  develop- 
ment of  vegetation,  and  there  may  be  a succession  of  plant 
associations  leading  to  the  formation  of  a scrubby  forest.  The 
pioneer  plants  here  are  predominantly  herbaceous,  and  various 
introduced  weeds  figure  prominently.  Indeed,  almost  no  other 
natural  habitat  supports  a greater  variety  of  weeds  than  shingle 
beaches.  In  this  connection  it  may  perhaps  be  remarked  that 


328 


George  E.  Nichols, 


there  seems  little  question  that  in  former  days,  in  so  far  as  they 
were  then  represented  in  this  region,  the  majority  of  the  plants 
popularly  classed  as  weeds,  and  which  to-day  thrive  in  a variety 
of  open  situations  created  by  man’s  activity,  were  restricted  to 
situations  such  as  gravel  slides ; boulder  plains,  sandy  flood  plains 
and  rocky  banks  along  streams ; and  sea  beaches.  Excluded 
through  competition  from  situations  edaphically  more  favorable 
to  them,  the  weeds,  which  as  a group  are  essentially  pioneers, 
have  always  flourished  in  these  open  situations. 

In  addition  to  the  weeds,  the  grasses  are  well  represented  on 
the  upper  beach  by  such  species  as  Ammophila  arenaria,  Dan- 
thonia  spicata,  Poa  compressa,  Poa  pratensis,  Festuca  rubra, 
and  occasionally  Elymus  arenarius,  while  the  sedge,  Carex 
silicea,  is  seldom  absent.  Other  common  herbaceous  species 
here  are  Fragaria  virginiana,  Potentilla  tridentata,  Geranium 
Robertianum,  Oenothera  muricata,  Ligusticum  scothicum,  Cam- 
panula rotundifolia,  and  Anaphalis  margaritacea.  Various 
xerophytic  mosses,  notably  Ceratodon  purpureus,  Racomitrium 
canescens,  Brachythecium  albicans,  Polytrichum  juniperinum, 
and  P oly trichum  piliferum,  thrive  in  open,  gravelly  soils,  while 
the  foliose  lichens,  Cladonia  rangiferina,  C.  syhatica,  and 
Stereocaulon  coralloides  may  also  be  represented.  But  the 
vascular  vegetation  is  by  no  means  restricted  to  herbaceous 
forms,  for  even  on  rocky  and  quite  exposed  parts  of  the  beach 
there  usually  are  scattered  shrubs  and  trees.  In  stony  situations 
the  plants  may  secure  a foothold  in  patches  of  gravel  between 
the  cobbles,  but  very  frequently  a favorable  substratum  is  created  j 
by  the  decomposition  of  logs  which  have  been  cast  up  by  storms. 
Of  the  shrubs,  Juniperus  communis  depressa,  Myrica  carolinensis, 
Rubus  idaeus  canadensis,  Empetrum  nigrum,  Gaylussacia 
baccata,  and  Vaccinmm  pennsylvanicum  are  quite  characteristic 
of  shingle  beaches,  and  Vaccinium  Vitis-Idaea  grows  well  in  j 
grassy,  gravelly  or  sandy  areas.  The  commonest  tree  is  the 
white  spruce,  though  the  balsam  fir  is  scarcely  less  frequent. 
Both  of  these  trees  often  exhibit  a weather-beaten  aspect,  but 
this  is  especially  true  of  the  balsam  fir.  On  the  beach  at  English- 
town  (Fig.  29)  grow  specimens  of  the  latter  which  measure 
less  than  two  feet  in  height  but  sprawl  out  on  the  ground  over  a 
radius  of  more  than  six  feet.  Their  low  stature  is  due  to  the 
repeated  killing  off  of  the  leader,  and  this  in  turn  is  probably 


Vegetation  of  Northern  Cape  Breton. 


329 

attributable  to  the  erosive  effect  of  wind-driven  snow  in  winter,  a 
phenomenon  which  will  be  referred  to  again  in  connection  with 
the  vegetation  of  the  barrens. 

Wherever  a shingle  beach  borders  on  the  mainland,  there  is 
a tendency  for  the  forests  of  the  adjoining  upland  to  encroach 
on  the  beach  (Fig.  27),  and  even  on  barriers  and  spits  scrubby 
forests  are  frequently  developed  on  the  older  parts  of  the  upper 
beach  (Fig.  29),  usually  on  lea  slopes  where  there  is  optimum 


Figure  29.— Stunted  balsam  firs  (foreground)  and  scrubby  forest  (left 
background)  on  shingle  beach;  St.  Ann’s  Bay;  compare  Fig.  33. 


protection  from  wind  and  wave.  Such  forests  are  quite  open, 
and  are  composed  almost  wholly  of  white  spruce  and  balsam  fir, 
which  seldom  reach  here  a height  of  more  than  twenty-five  feet. 
In  the  open  spaces  between  the  trees  grow  in  more  or  less  pro- 
fusion various  of  the  shrubs  and  herbaceous  plants  which  have 
been  listed  as  occurring  on  the  upper  beach,  while  certain  less 
xerophytic  species,  which  have  been  cited  earlier  as  characteristic 
of  the  pioneer  forest  stage  in  the  ordinary  upland  series,  are 
found  here  also.  Common  bryophytes  in  the  shade  of  the  trees 
are  Ptilidium  ciliare,  Dicranum  Bonjeanii,  Dicraniim  undulatum, 
Trans.  Conn.  Acad.,  Vol.  XXII  21  1918 


33° 


George  E.  Nichols, 


and  Hypnum  Schreberi.  On  the  whole,  the  aspect  of  such  a 
forest  is  quite  xerophytic. 

Association-types  of  sandy  beaches  and  dunes. — Aside  from 
their  frequent  association  with  shingle  beaches,  to  which 
reference  has  been  made  above,  broad  strips  of  sandy  beach 
fringe  the  mainland  here  and  there  in  somewhat  protected  situa- 
tions along  the  coast,  as  at  North  Bay  and  South  Bay,  Ingonish. 
Frequently  such  beaches  overlie  deposits  of  shingle  and  during 


Figure  30. — Sand  spit  at  North  Pond,  Aspy  Bay;  Ammophila,  etc.;  in 
the  distance,  Cape  North. 

heavy  storms  the  sand  may  be  completely  swept  away  from  the 
more  exposed  parts  of  the  beach.  The  finest  display  of  sandy 
beach  along  the  coast  of  northern  Cape  Breton  is  seen  at  Aspy 
Bay,  where  North  Pond  is  nearly  cut  off  from  the  ocean  by  a 
sand  spit  (Fig.  30),  which  is  fully  three  miles  long  and 
averages  perhaps  a hundred  yards  in  width.  South  Pond 
similarly  is  almost  shut  in  by  a shorter  but  much  broader  spit, 
on  which  have  been  built  up  a fine  series  of  sand  dunes. 

As  in  the  case  of  shingle  beaches,  the  lower  beach  here  is 
practically  plantless,  while  the  middle  beach  is  populated  by  a 


Vegetation  of  Northern  Cape  Breton.  331 

scattered  growth  of  annual  and  perennial  herbaceous  plants 
which  maintain  a precarious  foothold  on  the  shifting  sand.  The 
number  of  species  in  this  latter  zone  is  small,  the  only  forms 
noted  here  being  Ammophila  arenaria,  Salsola  Kali,  Arenaria 
peploides,  Cakile  edentula,  Lathyrus  maritimus,  Euphorbia  poly- 
gonifolia,  and  Mertensia  maritima.  The  lower  and  middle 
beaches  vary  in  width.  On  the  South  Pond  spit,  each  is  about 
150  feet  wide;  but  ordinarily  they  are  much  narrower.  The 


Figure  31. — Sand  dunes  with  forest  of  white  spruce,  etc.;  South  Pond, 
Aspy  Bay. 


upper  beach  likewise  varies  in  width ; at  South  Pond  it  is  fully 
250  feet  wide,  but  this  is  exceptional.  At  both  North  and  South 
Ponds  the  crest  of  the  beach  proper  is  perhaps  four  feet  above 
high  water  mark.  At  North  Pond  the  upper  beach  is  covered 
by  a broad,  low  dune  which  in  places  rises  to  a height  of  eight 
or  ten  feet  above  high  water  mark.  The  plant  cover  here  con- 
sists mainly  of  a rank,  open  growth  of  Ammophila,  with  which 
are  associated  Lathyrus  maritimus  and,  locally,  Elymus 
arenarius.  Over  limited  areas  on  the  lea  slope,  the  shrubs, 
Myrica  carolinensis  and  Rosa  virginiana,  have  replaced  the 
[;  Ammophila  association.  In  one  place  a scrubby  forest  has  been 


332 


George  E.  Nichols, 


buried  by  the  sand,  but  at  the  present  time  trees  are  scarce  and 
of  merely  sporadic  occurrence. 

The  South  Bay  spit  with  its  dunes  (Fig.  31),  from  the  stand- 
point of  physiographic  ecology,  affords  in  itself  a study  of 
exceptional  interest,  and  has  already  been  written  up  in  some 

detail  by  Dr.  Harvey  (T8). 
In  crossing  the  spit  from 
the  seaward  margin  on  the 
east  to  the  “pond,”  which  is 
between  one  and  two  miles 
wide,  one  encounters  in  order 
( 1 ) the  lower  beach,  (2) 
the  middle  beach,  (3)  the 
upper  beach,  and  ( 4 ) the 
salt  meadows  and  marshes 
which  border  the  spit  on  its 
western  side.  Along  the  sea- 
ward edge  of  the  broad 
upper  beach  is  a row,  some- 
times double  but  mainly 
single,  of  sand-dunes,  mostly 
less  than  six  feet  in  height, 
but  in  one  locality  rising  to 
fully  fifteen  feet.  Some  at 
least  of  the  dunes  have 
originated  in  moist  depres- 
sions, or  “pans,”  in  which 
grow  J uncus  balticus  littoralis 
and  Iris  versicolor.  On  many 
of  the  lower  dunes,  as  might 
be  expected,  the  sand-reed 
( Ammophila ) is  the  pre- 
dominant plant,  fulfilling  in 
connection  with  dune-formation  the  twofold  function  of  (1) 
breaking  the  force  of  the  wind  and  causing  it  to  drop  part  of  its 
burden  of  sand,  and  ( 2 ) binding  together  and  holding,  by  means 
of  its  copious,  slender  roots,  the  sand  which  thus  accumulates. 
More  often  than  not,  however  (Fig.  32),  the  sand-reed  is  absent 
and  in  its  place  occurs  a luxuriant  growth  of  wire-grass  ( Poa 
compressa) , which  seems  fully  competent  to  carry  out  the 
functions  elsewhere  performed  by  the  sand-reed. 


Figure  32. — Low  dunes  at  South 
Pond,  Aspy  Bay;  in  foreground, 
Poa  compressa  acting  as  a sand- 
binder. 


Vegetation  of  Northern  Cape  Breton. 


333 


On  the  lea  slopes  of  these  low  dunes,  trees  germinate,  pre- 
dominantly white  spruce,  but  some  balsam  fir.  The  reciprocal 
relation  between  these  trees  and  the  dunes  is  rather  striking. 
Germinating  in  the  first  place  in  the  shelter  of  the  low  dunes,  as 
the  trees  increase  in  size  they  afford  an  effective  wind-break, 
which  in  turn  is  largely  responsible  for  the  further  increase  in 
the  height  of  the  dunes.  The  bases  of  the  trees  may  be  covered 
to  a depth  of  six  feet  or  more  by  sand,  but  both  the  spruce  and 
the  balsam  are  able  to  accommodate  themselves  to  the  changed 
conditions  through  the  development  of  adventitious  roots  from 
the  buried  part  of  the  trunk.  The  highest  dunes  are  covered 
at  the  crest  with  good-sized  trees  which  have  thus  been  partially 
buried. 

The  dunes  very  likely  would  attain  a greater  height  here,  were 
it  not  for  the  fact  that  they  are  exposed  to  winds  from  two 
directions ; the  westerly  winds  which  sweep  across  the  pond 
tend  to  check  the  growth  of  the  dunes,  which  is  due  mainly  to 
the  easterly  winds  from  off  the  ocean. 

In  the  lea  of  the  dunes,  between  them  and  the  salt  meadows, 
is  a broad  stretch  of  low,  sandy  “back  beach,”  the  surface  of 
which  is  rolling,  and  is  covered  partly  by  an  open  coniferous 
forest,  partly  by  grassy  areas  with  scattered  trees.  Below  is 
given  a list  of  the  vascular  plants,  exclusive  of  certain  weeds, 
which  occur  more  or  less  abundantly  in  these  open  tracts. 


Juniperus  communis  depressa 
Panicum  implicatum 
Agrostis  alba  maritima 
Danthonia  spicata 
Festuca  rubra 
Arenaria  lateriflora 


Fragaria  virginiana 
Potentilla  tridentata 
Lechea  intermedia  juniperina 
Vaccinium  Vitis-Idaea 
Campanula  rotundifolia 
Leontodon  autumnalis 


The  grassy  sward  is  nowhere  very  close,  but  the  sand  is 
nearly  everywhere  hidden  by  the  two  mosses,  Tortilla  ruralis  and 
Dicranum  spurium,  and  species  of  Cladonia.  In  among  the  trees 
occur  a number  of  species  which  were  not  noted  in  the  more 
open  situations,  or  only  rarely  so,  such  as  Maianthemum 
canadense,  Trientalis  americana,  Rhus  Toxicodendron,  Ribes 
lacustre,  and  the  mosses,  Dicranum  undulatum  and  Hypnum 
Schreberi.  The  branches  of  some  of  the  white  spruces  support 
the  most  luxuriant  growth  of  the  dwarf  mistletoe  ( Arceuthobium 
pusillum ) that  the  writer  has  ever  seen. 


334  George  E.  Nichols, 

B.  Secondary  Formations  of  the  Xerarch  Series 

Formation-types  Resulting  Primarily  from  Human  Activity 

a.  ASSOCIATION-COMPLEXES  DUE  TO  CULTIVATION 

Notwithstanding  the  comparative  recency  with  which  this 
country  was  settled,  deserted  farms  are  a familiar  sight,  and 
abandoned  farmlands  in  all  stages  of  revegetation  are 
encountered.  It  is  only  through  constant  grazing  and  cutting, 
or  repeated  mowing,  that  pastures  and  meadows  can  be  kept 


Figure  33.— Cultivated  fields,  abandoned  pastures,  and  coniferous  second 
growth  forests  along  St.  Ann’s  Bay;  in  the  left  background,  the  shingle 
beach  which  nearly  encloses  St.  Ann’s  Harbor  (compare  Fig.  29). 


open,  for  the  rapidity  with  which  a neglected  field  reverts  to 
woodland  is  even  greater  here  than  in  southern  New  England. 
The  association-types  which  arise  in  the  course  of  secondary  suc- 
cessions subsequent  upon  cultivation  may  be  considered  under 
two  heads:  (1)  the  association-types  of  fallow  fields,  and  (2) 
the  association-types  of  abandoned  pastures. 

The  following  figures,  in  addition  to  those  introduced  here- 
with, illustrate  secondary  formations:  Figs.  3,  9,  15,  24,  41. 
42,  46. 


Vegetation  of  Northern  Cape  Breton. 


335 


The  association-types  of  fallow  fields. — For  several  years 
after  a plowed  field  has  been  abandoned  its  vegetation  may 
consist  largely  of  weeds.  Common  species  in  such  a habitat  are : 

Rnmex  Acetosella  Solidago  graminifolia 

Spergula  arvensis  Achillea  Millefolium 

Raphanus  Raphanistrum  Chrysanthemum  Leucanthemum 
Prunella  vulgaris  Leontodon  autumnalis 

Galeopsis  Tetraliit  Taraxacum  officinale 

Plantago  major  Cirsium  arvense 

In  the  early  stages  of  reclamation,  so  long  as  the  plants  are 
scattered  and  the  vegetation  relatively  open,  both  annual  and 
perennial  species  may  be  about  equally  well  represented.  But 
as  the  ground  comes  to  be  more  densely  populated,  most  of  the 
annuals  are  crowded  out  and  the  plant  cover  comes  to  consist 
almost  entirely  of  species  which  are  perennial.  Various  grasses, 
especially  Danthonia  spicata  and  Poa  pratensis,  appear  rather 
early  in  the  succession,  and  as  time  goes  on  these  come  to  com- 
prise a more  and  more  important  element.  Sooner  or  later  a 
continuous  mat  of  vegetation  is  developed,  in  which  the  grasses 
are  usually  the  predominant  plants,  and  the  formerly  bare  soil 
becomes  covered  over  by  a thin  turf.  Species  of  Cladonia  and 
Polytrichum  also  commonly  play  an  important  part  in  the 
development  of  the  turf.  With  the  formation  of  a grassy  sward, 
the  conditions  come  to  approximate  those  of  pastures.  A few 
shrubs  and  trees  may  have  appeared,  but  on  the  whole  the  suc- 
cession beyond  this  point  is  essentially  the  same  as  that  in 
abandoned  fields,  which  is  discussed  in  the  following  paragraphs. 

The  association-types  of  abandoned  fields. — The  predominant 
plants  in  open  fields  are  the  grasses.  In  dry  pastures  Danthonia 
spicata  and  Poa  pratensis  are  ordinarily  the  most  abundant 
species,  but  growing  along  with  these  and  contributing  to  the 
formation  of  the  thin  sward  may  be  various  perennial  weeds, 
particularly  any  of  those  mentioned  in  the  second  column  of  the 
preceding  list  as  characteristic  of  fallow  fields,  together  with 
other  herbaceous  perennials  such  as  Fragaria  virginiana,  Tri- 
folium repens,  and  Antennaria  neodioica.  Species  of  Cladonia 
and  Polytrichum  also  are  usually  present  here ; sometimes  the 
; ground  cover  consists  almost  wholly  of  Polytrichum  and 
Leontodon. 


336 


George  E.  Nichols, 


The  general  aspect  of  the  vegetation,  as  just  described,  is 
xerophytic.  Under  favorable  edaphic  conditions,  however,  it 
may  be  much  more  mesophytic.  In  moist  meadows  the  grass 
forms  a denser  growth  and  is  made  up  largely  of  species  such  as 
Poa  pratensis,  Agrostis  alba,  and  Anthoxanthum  odoratum. 
Common  associates  of  the  grasses  here  are  Euphrasia  purpurea 
Reeks  and  Rhinanthus  Crista- ga-lli.  The  Euphrasia  occupies 

much  the  same  ecological  position  in  the  fields  of  northern  Cape 
Breton  as  does  Houstonia  caerulea  in  those  of  southern  New 


Figure  34. — Abandoned  field  with  white  spruce  and  Dicksonia;  Bar- 
rasois. 

England.  Any  of  the  perennial  herbs  referred  to  above  may 
grow  in  moist  meadows,  but  here,  in  addition,  pronounced  meso- 
phytes,  such  as  the  orchids,  Habenaria  clavellata,  H . lacera,  and 
H.  psycodes,  are  also  frequent. 

Whenever  a field  is  permitted  to  run  wild,  Dicksonia  puncti- 
lobula  (Fig.  34),  Pteris  aquilina,  Anaphalis  margaritacea,  and 
other  herbaceous  perennials  which  grazing  or  haying  have  held 
in  check  tend  to  assert  themselves,  while  various  shrubs  may  also 
become  conspicuous.  Among  the  latter,  Juniperus  communis 
depressa,  Rubus  idaeus  canadensis  and  Vaccinium  pennsyl- 


Vegetation  of  Northern  Cape  Breton. 


33  7 


vanicnm  are  common  in  neglected  pastures,  while  Salix  hnmilis , 
Alnns  mollis  and  Spiraea  latifolia  are  frequently  prominent. 
But  while  Dicksonia  and  other  herbs  often  develop  luxuriantly, 
and  while  shrubs  may  sometimes  come  to  predominate  over  con- 
siderable areas,  on  the  whole  there  is  no  sharply  defined  inter- 
mediate successional  stage  between  grassland  and  coniferous 
forest.  As  a matter  of  fact,  trees  are  present  from  the  outset. 


Figure  35. — Reproduction  of  balsam  fir  and  spruce  in  abandoned  field, 
Barrasois. 

A close  examination  of  almost  any  grassy  field  will  usually 
reveal  the  presence  of  numerous  young  seedling  coniferous 
trees  (Fig.  35).  In  the  face  of  repeated  mowing  these  trees  will 
persist  for  several  years  and  are  ready,  whenever  the  opportunity 
offers,  to  grow  up  and  to  more  or  less  completely  occupy  the 
ground.  Grazing  may  check  tree  reproduction  but  seldom 
prohibits  it  entirely.  In  one  field  where  sheep  are  pastured  much 
of  the  year,  the  writer  counted  as  many  as  twelve  seedling  white 
spruces  to  the  square  yard.  The  browsing  of  cattle  may  check 
their  growth  and  is  responsible  for  various  grotesque  tree  shapes, 


338 


George  E.  Nichols, 


but  only  frequent  cutting  will  prevent  trees  from  eventually  gain- 
ing supremacy.  The  speed  with  which  grassland  may  become 
superseded  by  woodland  is  suggested  by  the  conditions  observed  in 
two  quadrats  (io  meters,  32.8  feet  square),  which  were  located 
in  fields  that  had  been  neglected  for  twelve  or  fifteen  years.  In 
one  case,  counting  only  specimens  which  were  more  than  a foot 
high,  there  were  ninety  trees  in  the  quadrat,  ranging  up  to  twelve 
feet  in  height  and  thirteen  years  in  age.  Of  these  trees,  thirty- 
four  were  white  spruce,  twenty-seven  balsam  fir,  twenty-seven 
paper  birch,  and  two  white  pine.  In  another  similar  quadrat 
there  were  fully  five  hundred  trees,  dead  or  alive,  ranging  up  to 
fifteen  feet  in  height  and  averaging  between  eight  and  fifteen 
years  in  age.  In  this  case,  the  trees  without  exception  were 
white  spruce.  These  quadrats  illustrate  the  varying  composition 
which  an  old  field  woodland  may  possess.  In  some  cases  there 
will  be  nearly  pure  stands  of  white  spruce,  in  others  intimate 
admixtures  of  this  tree  with  black  spruce,  balsam  fir,  and  paper 
birch.  In  the  vicinity  of  Baddeck,  and  in  a few  other  localities 
noted,  the  tamarack,  in  many  cases,  rivals  the  white  spruce  for 
the  position  of  prominence  in  abandoned  pastures.  The  local 
frequency  of  the  tamarack,  as  already  suggested,  is  attributable, 
without  much  question,  to  soil  conditions : indeed,  it  seems  quite 
possible  that  the  local  distribution  of  this  tree  might  prove  of 
value  as  an  indicator  of  the  capabilities  of  land  for  crop  pro- 
duction. It  seems  quite  probable  that  variations  in  the  composi- 
tion of  old  field  woodlands  can  be  correlated  still  further  with 
local  differences  in  soil,  etc.,  although,  so  far  as  the  observations 
of  the  writer  have  extended,  the  variations  might  well  be 
explained,  in  large  measure  at  any  rate,  by  the  proximity  of 
seed  trees  and  the  fortuitous  distribution  of  seed. 

The  changes  which  accompany  the  development  of  woodlands 
in  old  fields  can  best  be  brought  out  by  a specific  illustration:  a 
series  of  pastures  along  the  Barrasois  River  which  have  been 
abandoned  at  different  dates.  The  vegetation  of  the  pastures 
themselves  is  essentially  as  described  above.  The  pioneer  trees  are 
mostly  white  spruce.  These  germinate  prolifically,  especially  in 
places  where  there  is  a carpet  of  P olytrichum.  The  moss  carpet 
apparently  furnishes  an  ideal  seed  bed,  since  in  situations  where 
it  is  absent  reproduction  is  noticeably  sparser.  As  the  spruces 
mature,  forming  first  a rather  open  grove  (Fig.  36)  and  later 


Vegetation  of  Northern  Cape  Breton. 


339 


a closed  forest,  a sequence  of  changes  may  ensue  similar  to 
what  has  been  described  in  connection  with  the  later  phases  of 
the  rock  outcrop  succession.  By  the  time  the  grove  phase  has 
been  attained,  much  of  the  pasture  vegetation  has  vanished.  In 
its  place,  in  the  semi-shaded,  narrow  lanes  (or  spaces)  between 
the  trees  (or  groups  of  trees),  is  a more  or  less  continuous  bed 
of  moss,  growing  on  which  may  be  found  the  pioneer  representa- 
tives of  various  woodland  species  of  plants.  The  moss  carpet  at 
first  may  consist  of  Polytrichum  commune,  but  soon  this  is 


Figure  36. — Grove  of  white  spruce  in  former  pasture;  Barrasois. 
Photograph  by  Dr.  L.  H.  Harvey. 

largely  superseded  by  Hypnum  Schreberi.  Among  the  herba- 
ceous woodland  pioneers  noted  here  are  Lycopodium  complana- 
tum,  L.  clavatum,  Maianthemum  canadense,  Cornus  canadensis, 
Viola  incognita,  Epigaea  re  pens,  Linnaea  borealis  americana,  and 
Trientalis  americana.  Small  white  spruce  seedlings  grow  scat- 
tered over  the  moss  carpet,  but,  practically  speaking,  white  spruce 
reproduction  has  come  to  a standstill,  for  few  of  these  seedlings 
are  destined  to  mature. 

In  this  connection,  there  is  one  feature  of  a young  spruce 
forest  that  demands  special  comment.  On  the  ground  beneath 


34© 


George  E.  Nichols, 


the  trees  in  such  a forest  there  may  be  no  vegetation  whatever, 
but  only  a dry  layer  of  dead  spruce  needles,  comprising  what 
the  forester  familiarly  refers  to  as  “duff.”  The  absence  here  of 
plants  does  not  seem  to  be  attributable  directly  to  insufficient 
light.  In  remarking  recently  on  this  same  phenomenon,  Moore 
(’ 17 , pp.  156,  157)  has  concluded  that  the  lack  of  vegetation  is 
due  to  the  dryness  of  the  soil  which  results  from  the  interception 
of  the  precipitation  by  the  crowns  of  the  trees.  The  writer  had 
already  arrived  at  a conclusion  somewhat  as  follows.  During 
the  development  of  a group  of  young  spruces  in  the  open,  at 
first  there  is  ample  light  for  all.  But  later  on,  in  the  competition 
for  light  which  ensues  as  they  become  larger,  many  of  the  trees 
are  killed.  The  accumulation  on  the  ground  beneath,  both  of 
the  needles  which  fall  from  these  dead  trees  and  of  needles 
derived  from  the  shaded  branches  of  the  living  trees,  may 
take  place  so  rapidly  that  the  ground  vegetation  is  buried.  The 
formation  of  this  thick,  loose  layer  of  dry  needles  not  only 
wipes  out  the  original  ground  cover,  but,  because  of  its  dryness, 
prevents  any  new  vegetation  from  getting  a start.  This  process, 
initiated  while  the  tree  growth  is  still  open,  continues  during 
the  transition  from  the  grove  to  the  forest  stage  in  the  succes- 
sion. A layer  of  needles  several  inches  thick  may  collect  on  the 
forest  floor,  and  all  the  mosses  and  herbaceous  plants,  as  well  as 
the  seedling  trees  described  in  the  preceding  paragraph,  may  be 
exterminated.  The  extreme  paucity  of  vegetation  on  the  forest 
floor  which  results  in  this  manner  is  a very  characteristic  feature 
of  young  coniferous  forests.  Later  on,  as  the  forest  matures, 
the  trees  becoming  greatly  decreased  in  number  by  the  constant 
competition  for  light,  and  in  consequence  becoming  more  widely 
spaced,  the  rate  of  leaf-fail  gradually  slackens  so  that  a certain 
degree  of  equilibrium  is  brought  about  on  the  forest  floor.  It 
then  becomes  possible  for  a new  ground  cover  to  establish 
itself : Polytrichum  commune  and  Hypnttm  Schreberi  reappear, 
followed  shortly  by  Hylocomium  splendens,  and  a moss  carpet 
is  gradually  reestablished,  on  which  woodland  herbs  and  shrubs, 
together  with  seedlings  of  balsam  fir  and  other  trees  of  the 
coniferous  forest  association-type  become  increasingly  abundant. 
The  history  of  the  forest  beyond  the  grove  stage  of  the  succession 
is  practically  identical  with  what  has  been  described  in  connec- 
tion with  primary  successions. 


Vegetation  of  Northern  Cape  Breton.  341 

b.  ASSOCIATION-COMPLEXES  DUE  TO  FIRE 

Fire,  like  cultivation,  destroys  the  original  vegetation  and 
causes  the  institution  of  new  successional  series.  According  to 
the  completeness  of  the  devastation,  particularly  as  it  affects  the 
humus  layer  with  its  subterranean  plant  organs  and  its  micro- 
organisms, broadly  speaking,  two  lines  of  succession  may  be  dis- 
tinguished: one  where  the  humus  has  escaped  serious  injury, 
the  other  where  the  humus  has  been  destroyed.  Between  these 
there  of  course  are  intermediate  possibilities. 

Humus  little  injured. — Let  it  be  assumed  that  previous  to  the 
conflagration  a burned  area  has  supported  a forest  of  the  climax 
type.  Aside  from  the  annihilation  of  much  of  the  antecedent 
vegetation,  the  most  obvious  immediate  effect  of  fire  is  the 
removal  of  the  forest  cover  and  the  consequent  increased  illumi- 
nation of  the  forest  floor.  The  revegetation  of  such  an  area  is 
destined  to  be  accomplished  partly  through  the  agency  of  plants 
which  in  various  ways  have  survived  the  fire,  partly  through  the 
invasion  of  plants  from  other  sources.  Almost  the  first  after- 
effect of  the  fire  is  seen  in  the  rapid  spread  of  certain  herbaceous 
species  which  were  only  sparingly  represented  in  the  original 
forest,  but  which  are  able  to  flourish  in  the  new  environment. 
Cornus  canadensis  perhaps  nowhere  develops  more  luxuriantly 
than  in  burned  areas,  while  Linnaea  borealis  americana  and 
Maianthemum  canadense  also  thrive  here.  Of  the  shrubs  and 
small  trees  in  the  burned  forest,  Corylus  rostrata,  Acer  spicatum 
and  Viburnum  cassinoides  frequently  survive.  The  local 
herbaceous  element  in  the  flora  may  predominate  for  a longer 
or  shorter  period,  but  it  is  soon  augmented  by  an  extraneous 
element  in  which  the  following  species  are  usually  conspicuous : 
Lycopodium  clavatum  and  Gaultheria  procumbens;  Solidago 
bicolor  and  5".  macrophylla;  Pteris  aquilina  and  the  “fire-weeds,” 
Epilobium  angustifolium  and  Anaphalis  margaritacea,  which  fre- 
quently form  a rank  growth;  and  Rubus  idaeus  canadensis, 
which  within  a few  years  may  produce  an  almost  impenetrable 
tangle  over  the  entire  area. 

In  the  reestablishment  of  forests  in  burned  areas  of  this  sort, 
the  paper  birch,  as  elsewhere  in  the  northwoods,  is  everywhere 
the  conspicuous  pioneer.  This  tree,  it  will  be  recalled,  is  spar- 
ingly represented  in  the  regional  climax  forest.  After  a burn  it 
reproduces  rapidly,  partly  by  means  of  coppice  shoots  from 


342 


George  E.  Nichols, 


stumps  which  have  survived  the  fire,  partly  from  seed,  and  with 
its  rapid  rate  of  growth  it  quickly  gains  the  ascendancy  over 
other  trees  in  the  rising  forest.  Red  maple  also  frequently  plays 
an  active  role  in  reforestation,  reproducing  in  much  the  same 
manner  as  the  birch ; while  the  bird  cherry  and  any  of  the 
poplars  may  be  present  in  greater  or  less  abundance.  A point 
of  interest,  to  be  emphasized  in  this  connection,  is  that  the 
balsam  fir,  with  the  spruces,  may  appear  at  a very  early  stage 


Figure  37. — Succession  after  a burn;  balsam  fir  coming  in  under  paper 
birch ; northwestern  Maine. 


in  the  succession : in  fact,  their  seedlings  may  be  present  from 
the  outset.  But,  on  account  of  their  relatively  slow  growth  in 
the  shade  cast  by  the  birch  canopy,  the  conifers  continue  to 
occupy  a position  of  subordinate  importance  for  many  years 
(Fig.  37).  By  the  time  a hundred  years  has  elapsed,  however, 
a marked  change  in  the  character  of  the  forest  has  taken  place; 
for  by  this  time  the  balsam  fir  Fas  usually  become  the  pre- 
dominant tree.  This  latter  phase  in  the  succession  is  well 
illustrated  by  an  old  bum  forest  near  Indian  Brook.  Here  the 
bulk  of  the  mature  stand  consists  of  balsam  fir  intermixed  with 


Vegetation  of  Northern  Cape  Breton. 


343 


frequent  white  spruces,  scarcely  any  of  the  balsams  being-  more 
than  ten  inches  in  diameter.  Paper  birch  is  rarely  present  in  the 
younger  growth,  but  is  represented  abundantly  by  scattered  older 
specimens  ranging  up  to  a foot  and  a half  in  diameter,  while  the 
ground  beneath  is  strewn  with  the  remains  of  fallen  trees.  Large 
red  maples  are  frequent  and  one  large  hemlock  with  a healed 
fire  scar  was  noted,  obviously  a relict  of  the  former  forest. 

The  ultimate  association-type  of  the  burn  succession  is  a 
forest  of  the  regional  climax  type,  provided  edaphic  conditions 


Figure  38. — View  along  coast  north  of  Neil’s  Harbor:  barrens  and 
second  growth  forest,  mostly  white  spruce;  aspect  largely  the  result  of 
repeated  burning.  Photograph  by  Dr.  L.  H.  Harvey. 


are  favorable  to  its  development.  Indeed,  very  often  the  beech 
and  others  of  the  climax  trees  beside  those  already  mentioned 
may  appear  early  in  the  series,  arising  either  from  coppice 
sprouts  or  from  seed.  It  seems  hardly  necessary  to  describe  the 
changes  in  the  undergrowth  which  accompany  the  development  of 
the  forest. 

Humus  destroyed. — There  are  extensive  tracts  of  land  along 
the  eastern  coast  of  northern  Cape  Breton,  particularly  between 
North  Bay,  Ingonish  and  Aspy  Bay  (Fig.  38),  which  it  is  pre- 
sumed were  formerly  covered,  very  largely  at  any  rate,  with 
deciduous  forests,  but  which  have  suffered  so  severely  from 
fires  that  at  one  time  or  another  not  only  the  greater  part  of  the 


344 


George  E.  Nichols, 


vegetation,  but  most  of  the  humus  as  well  has  been  consumed. 
In  areas  of  this  sort  succession  must  start  all  over  again  from 
near  the  bottom  and  a sequence  of  stages  similar  to  what  has 
been  described  in  primary  successional  series  may  be  observed. 
To  be  sure,  succession  in  an  area  which  has  been  denuded  by 
fire  differs  in  certain  respects  from  a primary  succession,  owing 
chiefly  to  the  fact  that  even  repeated  fires  fail  to  completely 
annihilate  all  the  previously  existing  humus  and  plant  life,  and 


Figure  39. — White  spruce  reproduction  in  an  area  which  has  been 
repeatedly  cut  and  burned ; South  Bay,  Ingonish. 

that  the  relicts  which  have  thus  survived  may  play  an  important 
part  in  the  succession.  But  it  is  hardly  worth  while  to  attempt 
to  depict  the  stages  in  detail.  In  general  it  may  be  stated  that, 
just  as  in  the  case  of  primary  successions,  there  is  a marked 
variation  in  the  nature  of  the  primitive  associations,  due  to  local 
differences  in  the  nature  of  the  substratum,  etc.,  but  that  all 
successional  series  tend  to  merge  in  the  formation  of  forest. 

Abundance  of  white  spruce  the  result  of  fire  and  cultivation. — 
At  the  present  day,  throughout  the  region  of  deciduous  forests, 
wherever  tracts  of  land  have  been  cultivated  and  then  abandoned 


Vegetation  of  Northern  Cape  Breton. 


345 


or  have  been  ravaged  by  repeated  fires,  white  spruce,  with  local 
exceptions,  is  everywhere  the  most  abundant  tree  of  second 
growth  forests.  The  explanation  of  this  fact  is  obvious.  The 
white  spruce  is  essentially  a pioneer.  It  seeds  prolifically  and 
rapidly  colonizes  open  grounds  of  almost  any  description 
(Fig.  39).  The  effect  of  cultivation  and  fire  in  destroying  the 
seedlings  of  balsam  fir  and  other  trees,  which  otherwise  might 
have  dominated,  enables  the  spruce,  with  its  capacity  for  rapid 
reproduction  in  the  open,  to  establish  itself  and  to  make  head- 


Figure  40. — Blueberry  barren  near  Frizzleton. 


way  which  otherwise  would  be  impossible.  The  common  practice 
of  burning  over  woodlots  in  order  to  keep  them  open  for 
pasturage  or  for  some  other  reason,  naturally  favors  the  spruce. 
In  brief,  the  combined  effect  of  cultivation  and  fire  is  to  arrest 
the  succession,  so  that  it  rarely  progresses  beyond  the  pioneer 
forest  stage. 

Blueberry  barrens. — Among  the  most  unique  features  of  the 
interior  plateau  of  northern  Cape  Breton  are  the  Barrens. 
These  natural  barrens,  which  will  be  described  later,  should  not 
be  confused  with  the  barrens  of  the  lowlands  (Fig.  40),  which 
are  the  result  of  repeated  fires,  usually  set  intentionally  every 
few  years  in  the  interest  of  the  blueberry  crop.  Extensive  blue- 


346 


George  E.  Nichols, 


berry  barrens  of  this  sort  are  found  in  the  Margaree  district, 
where  they  may  occupy  hundreds  of  acres.  The  predominant 
plants  in  such  tracts  are  the  blueberries,  Vaccinium  pennsyl- 
vanicum  and  V.  canadense,  with  which,  though  far  less  abundant, 
are  associated  other  ericaceous  shrubs,  such  as  Kalmia  angusti- 
folia,  Vaccinium  Vitis-Idaea,  Gaultheria  procumbens,  and 
Ledum  groenlandicum.  Various  herbaceous  plants  occupy  a 
prominent  position,  notably  Pteris  aquilina,  Danthonia  spicata 
and  Aster  multiflorus,  while  Cladonia  rangiferina  and  the 
mosses,  Polytrichum  commune,  P.  juniperinum,  and  Hypnum 
Schreberi,  are  common.  The  ecological  aspect  is  that  of  a heath, 
though  there  are  scattered  trees,  mainly  tamarack  and  white 
spruce.  The  balsam  fir  is  virtually  absent. 

Left  to  itself,  such  an  area  becomes  forested  within  a few 
years.  The  process  of  reclamation  is  graphically  illustrated  by  j 
one  area  examined,  which  adjoins  a large  heath,  but  is  separated 
from  it  by  a highway  that  has  acted  as  a “fire  line.”  This  area 
is  now  occupied  by  an  open  forest  of  tamarack  and  white  spruce. 
The  balsam  fir  is  absent  from  among  the  larger  trees,  but  is 
abundantly  represented  in  the  young  growth.  The  heaths  are 
present  in  greatly  reduced  abundance,  as  compared  with  the 
barren  area  across  the  road,  and  the  moss  carpet  has  become 
correspondingly  more  luxuriant. 

C.  ASSOCIATION-COMPLEXES  DUE  TO  LOGGING 

The  indiscriminate  removal  of  the  merchantable  timber  in  a 
climax  forest  by  logging  usually  has  little  effect  on  the  future 
composition  of  the  forest,  provided  the  area  escapes  being  burned 
over.  Some  trees,  notably  the  paper  birch  and  balsam  fir,  tend 
to  become  somewhat  more  abundant  here,  and  frequently  pioneer 
species  such  as  the  aspens  are  able  to  establish  themselves 
temporarily  in  cut-over  tracts.  But,  on  the  whole,  the  forest 
may  be  said  to  regenerate  itself  through  the  younger  generation 
of  trees  which  was  present  in  the  original  forest.  Where  a forest 
is  lumbered  discriminately,  as  is  frequently  done  for  fir  and 
spruce  alone,  it  is  of  course  obvious  that  the  detailed  physiognomy 
of  the  forest  may  be  quite  appreciably  altered.  Where  the 
removal  of  the  timber  is  followed  by  burning,  most  of  the 
younger  trees  are  destroyed  and  complete  regeneration  is 


Vegetation  of  Northern  Cape  Breton.  347 

impossible.  This  latter  point  is  well  illustrated  by  conditions 
near  an  old  settlement  along  Indian  Brook,  which  has  been 
deserted  for  many  years.  The  climax  forest  was  cut  over  in 
two  adjoining  tracts,  one  of  which  was  afterward  burned  over, 
the  other  not.  To-day,  perhaps  forty  years  after  cutting,  the 
unburned  area  is  covered  by  a forest  of  yellow  birch,  sugar 
maple,  and  other  climax  trees,  with  scattered  specimens  of  paper 
birch  and  large-toothed  aspen  ( Populus  grandidentata) . The 
burned  area,  on  the  other  hand,  supports  an  almost  pure  forest 
of  paper  birch.  In  both  forests  the  balsam  fir  is  the  most 
conspicuous  undertree. 

C.  Primary  Formations  of  the  Hydra^rch  Series 

i.  The  Formation- types  of  Lakes  and  Ponds  Inland 

a.  introductory 

The  ecological  relationship  of  lakes  and  swamps. — For  pur- 
poses of  convenience,  lakes  and  swamps  are  here  treated  under 
separate  headings,  but,  broadly  speaking,  they  belong  to  the 
same  family  and  there  is  no  sharp  dividing  line  between  them. 
Through  the  activity  of  various  agencies  a lake  or  pond  may 
become  filled  in  and  converted  into  a swamp.  The  manner  in 
which  this  transformation  may  be  accomplished  by  plants, 
together  with  the  changes  in  vegetation  which  accompany  the  pro- 
cess, is  outlined  in  the  following  paragraphs,  quoted,  with  slight 
alterations,  from  an  earlier  paper  by  the  writer  (’15,  pp. 
175-178)  : 

The  important  role  commonly  played  by  plants  in  the  conversion  of 
lakes  into  swamps  has  long  been  recognized.  When  the  plants  in  a lake 
die,  their  remains  sink  to  the  bottom  where,  because  of  insufficient 
oxidation,  the  vegetable  debris  is  only  partially  decomposed.  In  this  way 
there  collects  on  the  floor  of  the  lake  a layer  of  vegetable  muck,  or  peat; 
and  through  the  continued  addition  of  fresh  layers  the  deposit  is  gradu- 
ally thickened  and  built  upward.  This  constructive  process  may  go  on 
until  ultimately  the  surface  of  the  deposit  reaches  the  level  of  the  water, 
when  the  lake  gives  way  to  a swamp.  But  the  rate  at  which  the  sub- 
stratum is  built  up  and  the  length  of  time  which  elapses  before  it  reaches 
the  water  level  varies  greatly  in  different  parts  of  a lake.  Plants  grow 
most  luxuriantly  in  shallow  water ; they  may  be  practically  absent  from 
the  deeper  areas.  It  follows,  therefore,  that  the  accumulation  of  muck 
: or  peat  proceeds  much  more  rapidly  in  shallow  than  in  deep  water — so 


34§ 


George  E.  Nichols, 


much  so,  in  fact,  that  the  shoreward  parts  of  a lake  may  have  become 
completely  filled  in  before  any  appreciable  accumulation  has  taken  place 
in  the  deeper  areas.  The  filling  in  of  deep  lakes  usually  proceeds  centri- 
petally.  This  is  due  to  the  fact  that  the  shoreward  zones  of  vegetation,  in 
consequence  of  their  more  vigorous  growth,  exhibit  a tendency  to  push 
outward  into  deeper  water.  Where  this  tendency  is  pronounced,  the  shoal 
water  zones  may  completely  override  the  deeper  water  zones,  at  the  same 
time  causing  the  lakeward  slope  of  the  deposit  to  become  much  steeper. 
The  filling  in  of  the  deeper  parts  of  a lake  may  also  be  effected  to  a 
varying  degree  by  the  accumulation  of  loose  debris  from  the  adjoining 
shallows  or  by  the  deposition  of  sediment  in  flood  time,  while  various 
plankton  forms  may  contribute  in  a small  measure  to  the  deposit. 

Coincident  with  the  upbuilding  of  the  substratum  through  the  deposition 
of  muck  or  peat,  as  outlined  in  the  preceding  paragraph,  transformations 
occur  in  the  character  of  the  vegetation  growing  on  the  lake’s  bottom. 
For,  as  the  depth  of  the  water  diminishes,  it  becomes  possible  for  plants 
to  develop  which  were  unable  to  grow  in  the  deeper  water.  And  as 
these  shallow  water  plants  increase  in  number  and  abundance,  they  may 
crowd  out  and  eventually  replace  the  deeper  water  species.  Thus  there 
may  follow  one  another  a series  of  plant  associations,  each  one  of  which, 
by  helping  to  raise  the  bottom  of  the  lake  to  a higher  level,  prepares  the 
way  for  less  hydrophytic  associations,  but  at  the  same  time,  by  so  doing, 
brings  about  its  own  extermination. 

It  is  a familiar  fact  that  the  plants  which  fringe  the  edges  of  so 
many  lakes  are  commonly  massed  in  more  or  less  definite  bands  or  zones 
that  tend  to  be  concentric  with  respect  to  the  deeper  parts  of  the  lake. 
The  floristic  composition  of  these  zones  in  any  given  lake  is  determined 
largely  by  the  ecological  requirements  of  the  various  species  of  plants 
which  happen  to  be  present,  in  relation  to  the  depth  and  clearness  of 
the  water  . . . Reference  has  already  been  made  to  the  succession  of 
plant  associations  which  accompanies  the  building  up  of  the  lake  bottom. 
It  has  been  found  that  this  dynamic  Vertical  Succession  corresponds 
closely  with  the  apparently  static  Horizontal  Zonation  just  outlined 
This  general  coordination  between  the  contemporaneous  hori- 
zontal sequence  of  zones  and  the  historical  or  vertical  order  of  suc- 
cession has  been  verified  repeatedly  by  the  stratification  of  plant  remains 
observed  in  peat  deposits,  and  is  of  great  assistance  in  reconstructing  the 
past  or  predicting  the  future  course  of  events  in  any  specific  locality. 

Of  course,  not  all  swamps  have  originated  in  the  manner  just 
described  (see  further  under  head  of  swamps)  ; neither,  on  the 
other  hand,  do  all  lakes  exhibit  any  pronounced  tendency  to 
become  converted  into  swamps.  For  reasons  which  are  not 
always  clear,  there  is  the  greatest  variation  in  the  speed  at  which 
the  transformation  is  brought  about,  and  in  many  lakes,  not 
only  does  there  seem  to  be  scarcely  any  tendency  toward  swamp 


Vegetation  of  Northern  Cape  Breton. 


349 


formation,  but  little  change  would  appear  to  have  taken  place 
at  any  time  since  their  formation. 

Geological  and  other  factors  influencing  the  distribtition  and 
vegetation  of  inland  lakes. — The  majority  of  the  lakes  and  ponds 
in  the  lowland  of  northern  Cape  Breton  are  glacial : they  occupy 
depressions  which  have  resulted  from  glacial  activity  (see 
further  discussion  in  Nichols  ’15,  pp.  170-171).  In  calcareous 
districts,  however,  particularly  in  localities  where  there  are 


Figure  41. — Freshwater  Lake,  South  Bay,  Ingonish ; cut  off  from  ocean 
by  a shingle  beach ; in  distance,  Middle  Flead,  mostly  granitic ; in  right 
foreground,  a gypsum  outcrop ; second  growth  forests  of  white  spruce 
and  balsam  fir.  Photograph  by  Dr.  L.  H.  Flarvey. 

extensive  deposits  of  gypsum,  “sink  holes”  due  to  subterranean 
erosion  are  common,  and  these  frequently  are  occupied  by  ponds. 
Still  a third  type  of  water  basin,  due  entirely  to  vegetative 
activity,  is  encountered  on  the  plateau,  and  will  be  described  in 
some  detail  later. 

In  their  influence  on  the  vegetation  of  lakes  and  ponds,  drain- 
age and  permanency  are  factors  of  considerable  significance. 
The  effect  of  drainage  will  be  discussed  presently  in  connection 
with  the  formation-types  of  swamps.  The  effect  of  permanency 
is  seen  in  comparing  the  vegetation  of  permanent,  with  that  of 


35° 


George  E.  Nichols, 


periodic,  lakes  or  swamps.  Permanent  and  periodic  lakes  and 
swamps,  as  related  to  topography  and  ground  water  level,  have 
been  fully  discussed  in  the  writer’s  paper  referred  to  above  (’15, 
pp.  1 72-1 75). 


b.  THE  ASSOCIATION-COMPLEXES  OF  WELL-DRAINED  LAKES  AND 

PONDS 


The  association-types  of  permanent  lakes. — Freshwater  Lake 
(Fig.  41)  and  Warren  Lake,  at  Ingonish,  may  be  taken  as  repre- 
sentative examples  of  fairly  large,  well-drained  lakes.  Except 
for  Chara  and  various  algae  there  is  little  vegetation  below  a 
depth  of  six  feet.  The  majority  of  aquatic  plants  grow  best  in 
water  less  than  three  feet  deep.  Along  sandy  shores,  which  are 
the  prevailing  type  in  both  ponds,  the  following  aquatic  species 
are  more  or  less  abundant. 


Chara  sp. 

Fontinalis  sp. 

Isoetes  e chinos p ora  Braunii 
Sparganium  angustifolium 
Potamogeton  Oakesianus 
Potamogeton  hetcrophyllus 
Potamogeton  bupleuroides 
Glyceria  borealis 
Scirpus  subterminalis 


Eleocharis  paluslris  vigens 
Scirpus  americanus 
Juncus  militaris 
Nymphaea  advena 
Ranunculus  Flammula  reptans 
Myriophyllum  humilis 
Nymphoides  lacunosum 
Eriocaulon  septangulare 
Lobelia  Dortmanna 


Nymphaea  and  Nymphoides  are  the  commoner  forms  in  the 
deeper  shallows.  Eriocaulon  often  forms  a bright  green  carpet 
on  the  bottom  in  water  three  or  more  feet  deep,  but  seldom 
flowers  where  it  is  more  than  a foot  deep:  Ranunculus  forms 
similar  carpets  in  shallow  water,  but  flowers  only  on  the  shore. 
In  places  Juncus  and  Isoetes  grow  in  profusion.  But  for  the 
most  part  the  sandy  bottom  is  only  sparsely  covered  by  vege- 
tation. It  might  be  added  that  Carex  aquatilis,  not  noted  in 
either  of  these  lakes,  is  a frequent  form  along  the  shores  of  low- 
land lakes,  locally  giving  rise  to  marshy  marginal  swamps 
similar  to  those  to  be  described  later  in  connection  with  lakes  in 
the  highlands. 

The  narrow  sandy  beach,  between  high  and  low  water  marks, 
supports  a scanty  growth  of  herbaceous  species,  among  them 


Vegetation  of  Northern  Cape  Breton.  351' 

Equisetum  arvense,  Juncus  articulatus,  and  Ranunculus  Flam- 
mula  reptans.  Above  high  water  mark  there  is  ordinarily  a 
fringe  of  Myrica  Gale  (nearest  the  water)  and  Alnus  incana. 

Muddy  shores  are  developed  to  some  extent  in  sheltered 
situations.  Here  the  aquatic  vegetation  includes  most  of  the 
species  already  listed,  and  in  addition  Utricularia  intermedia  and 
U.  vulgaris.  Certain  other  species,  mostly  amphibious,  grow  in 


Figure  42. — Fresh  pond  behind  shingle  beach,  well  drained  by  seepage 
through  barrier;  Typha  latifolia  in  left  foreground;  Barrasois. 


shallow  water  or  on  the  mucky  shore,  which  is  swampy  at  low 
water.  These  latter  include:  Sphagnum  sp.,  Drepanocladus 

fluitans,  Dulichium  arundinaceum,  Iris  versicolor,  Potentilla 
palustris,  Hypericum  virginicum,  Slum  cicutaefolium,  and 
Lysimachia  terrestris.  As  along  sandy  shores,  the  sweet  gale 
and  alder  fringe  the  shore  at  high  water  mark.  Along  sandy 
shores  there  is  little  evidence  of  succession,  but  along  muddy 
shores  there  is  a tendency  for  swamps  to  develop. 

The  association-types  of  permanent  ponds. — Small  ponds 
(Figs.  26,  42)  may  differ  little  from  lakes  in  the  character  of 


352 


George  E.  Nichols, 


their  vegetation.  But,  on  the  whole,  aquatic  plants  are  apt  to 
be  relatively  more  abundant  here  by  reason  of  the  lesser  depth  of 
the  water,  its  comparative  quietness,  etc.  Largely  because  of  the 
absence  of  any  appreciable  amount  of  wave  action,  the  shores 
of  small  ponds  tend  to  be  more  muddy  than  those  of  the  larger 
bodies  of  water.  The  vegetation  of  sandy  shores  is  similar  to 
what  has  been  described  above,  and  the  same  is  true  in  general 
of  muddy  shores.  Here,  however,  there  is  often  a rank  growth 
of  cat-tails  ( Typha  latifolia ) and  bulrushes  ( Scirpus  occidentalis, 
S.  cyperinus,  S.  atrocinctus,  etc.),  through  the  activity  of  which 
the  pond  tends  to  become  filled  in  and  converted  into  a swamp. 

Sink-hole  ponds  frequently  exhibit  the  phenomenon  of  marl- 
formation  (see  Nichols  ’15,  pp.  194-196).  In  such  ponds  there 
is  usually  a luxuriant  growth  of  Chara,  one  of  the  most  impor- 
tant marl-forming  plants,  and  of  various  algae.  Among  the 
prominent  aquatic  seed  plants  here  may  be  Potamogeton  pecti- 
natus  and  P.  pusillus.  Leaves  and  stems  of  all  submersed  forms 
are  usually  incrusted  with  a thin,  whitish,  flaky  deposit  of  marl. 

The  association-types  of  periodic  ponds. — Periodic  ponds  are 
not  sharply  delimited  from  permanent  ponds  on  the  one  hand 
or  from  periodic  swamps  on  the  other.  Very  shallow  depres- 
sions, which  during  the  growing  season  contain  water  for  only 
a brief  period,  are  commonly  occupied  by  a rank  growth  of 
such  species  as  Scirpus  cyperinus  and  A.  atrocinctus,  J uncus 
effusus  and  J.  brevicaudatus,  and  Iris  versicolor.  In  the  case  of 
ponds  which  disappear  completely  only  for  a short  period  dur- 
ing the  summer,  there  may  be  a striking  concentric  zonation  of 
plant  associations.  In  one  instance,  for  example,  the  wetter  cen- 
tral area  is  largely  occupied  by  the  moss,  Amblystegium  riparium. 
Proceeding  from  here  toward  high  water  level  there  are 
encountered  (z)  a zone  of  more  or  less  amphibious  species  such 
as  S parganium  americanum,  Juncus  effusus,  Ranunculus  Flatn- 
mula  reptans,  Hypericum  canadense,  Lysimachia  terrestris,  and 
Slum  cicutaefolium ; ( 2 ) a zone  of  Iris  versicolor;  (3)  a zone 
of  Alnus  incana.  Elsewhere  Eleocharis  palustris  and  the  species 
cited  earlier  in  this  paragraph  may  be  prominent  as  marginal 
plants,  while  in  some  cases  the  liverwort,  Marchantia  poly- 
morpha,  develops  profusely  on  the  muddy  shores  of  periodic 
ponds. 


Vegetation  of  Northern  Cape  Breton. 


353 


C.  THE  ASSOCIATION-COMPLEXES  OF  UNDRAINED  LAKES  AND 

PONDS 

The  association-types  of  permanent  ponds. — Sink-hole  ponds 
commonly  have  no  visible  outlet  and  are  practically  undrained. 
Aquatic  vegetation  as  a rule  is  luxuriantly  developed  here,  but 
varies  greatly  in  its  floristic  composition,  even  in  neighboring 
ponds.  In  one  small  pond,  for  example,  Potamogeton  natans  is 
practically  the  only  species  present;  in  another,  Chora;  in 
another.  FontinaMs  gigantea;  while  in  still  another,  Chara, 
Fontinalis  gigantea,  and  Potamageton  pusillus  grow  inter- 
mixed. Such  ponds  fluctuate  more  or  less  in  level  from  season 
to  season  and  the  marginal  vegetation  resembles  that  of  periodic 
ponds. 

Of  particular  interest,  in  view  of  their  subsequent  history, 
are  the  undrained  ponds  in  which  originate  peat  bogs.  The 
water  in  these  fluctuates  very  little  in  level  from  season  to  season, 
and  while  the  ponds  may  be  small  in  area  they  are  usually 
fifteen  or  more  feet  in  depth.  Depressions  of  this  sort  are  by 
no  means  common  near  the  coast,  and  most  of  those  which  were 
discovered  had  already  attained  the  bog  stage  in  their  develop- 
ment. It  is  of  interest  to  note,  however,  that  the  pioneer  vege- 
tation in  and  about  these  ponds  is  similar  in  most  respects  to  that 
of  other  ponds.  The  aquatic  vegetation  includes  Nymphaea 
advena,  species  of  Potamogeton,  and  various  aquatic  mosses 
and  algae.  Chara,  however,  seems  to  be  rare  or  absent.  In  the 
shallow  water  near  the  margin  may  grow  Sparganium 
americanum , Eriocaulon  septangulare,  Carex  Psendo-Cyperus, 
Potentilla  palustris,  and  Lobelia  Dortmanna.  Along  the  more 
or  less  mucky  shores  may  occur  herbaceous  species,  such  as 
Onoclea  sensibilis,  various  sedges,  Iris  versicolor,  Lysimachia 
terrestris,  Hypericum  virginicum,  and  Lycopus  americanus; 
and  shrubs,  such  as  Myrica  Gale,  Alnus  incana,  Rosa  nitida,  and 
Ilex  verticillata.  The  most  striking  difference  between  these  and 
ordinary  ponds  is  seen  in  the  frequently  luxuriant  development 
of  various  species  of  Sphagnum,  the  significance  of  which  will 
be  pointed  out  later.  The  marginal  shrubs  here  also  commonly 
include  Chamaedaphne  calyculata  and  Kalmia  angustifolia,  both 
of  which  are  typical  bog  forms. 

The  association-types  of  periodic  ponds. — Periodic  undrained 
ponds  scarcely  differ  in  their  vegetation  from  periodic  well- 


354 


George  E.  Nichols, 


drained  ponds,  since  essentially  the  same  end  is  accomplished 
through  the  periodic  drying  up  of  the  pond  as  might  be  attained 
through  drainage.  They  therefore  require  no  special  comment. 

2.  The  Formation- types  of  Lake-  and  Spring-swamps 

Inland 

a.  INTRODUCTORY 

Lake-,  spring-,  and  precipitation-swamps. — Swamps  which 
have  originated  in  the  manner  described  earlier,  through  the 
filling  in  of  lakes  by  vegetation,  may  be  designated  Lake-swamps. 
Many  swamps,  however,  probably  the  majority  of  those  in  the 
lowland,  owe  their  existence  to  the  relation  between  topography 
and  ground  water  level,  i.  e.,  to  the  presence  of  spring  or  seepage 
water.  Such  swamps  may  be  designated  Spring-swamps  (see 
Nichols  ’15,  pp.  184,  192).  Lake-  and  spring-swamps  are  wide- 
spread in  their  distribution  throughout  most  regions.  In  regions 
like  the  one  under  consideration,  where  precipitation  is  high  and 
the  evaporating  power  of  the  air  low,  there  is  still  a third  type 
of  swamp  whose  existence  is  dependent  very  largely  on  direct 
atmospheric  precipitation.  Swamps  of  this  sort,  well  exemplified 
by  the  raised  bogs  of  the  high  interior  plateau,  may  be  desig- 
nated Precipitation-swamps. 

The  ecological  significance  of  drainage. — In  his  study  of  the 
geographical  distribution  and  ecological  relations  of  bog 
associations  in  eastern  North  America,  Transeau  (’03,  p.  420) 
arrived  at  the  conclusion  that  “the  ‘drained  swamp’  and 
‘undrained  swamp’  classification  will  not  hold  over  any  great 
area.”  Drainage,  however,  has  been  employed  as  a basis  of 
classification  by  Cowles  (’01,  pp.  145-156)  and  others,  and  it  is 
the  conviction  of  the  writer  that,  from  the  standpoint  of  physio- 
graphic ecology,  this  factor  affords  by  far  the  most  fundamental 
criterion  yet  conceived,  at  least  for  the  classification  of  the  lakes 
and  swamps  in  the  inland  group.  The  relationship  between 
cause  and  effect  may  often  be  obscure,  since  the  influence  of 
drainage  is  commonly  expressed  indirectly  through  other,  more 
direct  factors ; but,  in  the  last  analysis,  drainage,  more  than  any 
other  single  factor  or  set  of  factors,  seems  to  have  a vital 
influence  on  the  vegetation,  through  its  effect  on  the  aeration  of 
the  soil  and  on  the  accumulation  therein  or  removal  therefrom 


Vegetation  of  Northern  Cape  Breton.  355 

of  various  deleterious  substances,  as  well  as  on  other  peculiari- 
ties of  the  substratum  with  which  the  character  of  the  vege- 
tation may  be  more  directly  correlated  (in  this  connection,  see 
Rigg  T6;  also  Harper  T8,  pp.  27-31). 

Drainage  as  a basis  of  classification. — In  treating  the  lakes 
and  swamps  of  the  inland  group  in  northern  Cape  Breton,  drain- 
age has  been  selected  as  the  most  fundamental  basis  of  classifi- 
cation. On  this  basis  the  lakes  and  ponds  have  been  divided 
into  two  groups,  well-drained  and  undrained,  and  the  swamps 
into  three,  well-drained,  poorly  drained,  and  undrained.  The 
practical  application  of  any  scheme  of  classification  of  course 
has  its  limits,  owing  to  the  difficulty,  if  not  the  impossibility,  of 
adequately  correlating  cause  and  effect,  and  whatever  factors 
are  selected  as  criteria,  all  sorts  of  intergrading  conditions  are 
encountered.  Particularly  in  the  case  of  swamps  is  the  com- 
plexity of  the  situation  enhanced  in  a cool,  humid  region  such  as 
this  by  the  fact  that  atmospheric  factors  may  react  on  the  vege- 
tation in  such  a manner  as  to  neutralize  to  a greater  or  less 
degree  the  influence  of  dissimilar  edaphic  conditions. 

During  the  course  of  the  present  investigations  in  northern 
Cape  Breton,  the  writer  has  examined  several  hundred  different 
lakes  and  swamps.  In  a number  of  the  swamps,  in  addition  to 
observations  on  the  surface  conditions,  soundings  were  taken 
with  a fifteen  foot  iron  rod  (summer  of  1915).  By  this  means 
it  was  possible  (1)  to  ascertain  the  depth  of  the  underlying 
vegetable  deposit;  (2)  by  the  attachment  of  a Davis  peat-sampler 
(see  Bastin  & Davis  ’09,  p.  61),  to  determine  the  character  of  the 
deposit  at  different  depths;  and  (3)  with  the  aid  of  a hand-level, 
to  figure  out  the  topography  of  the  underlying  terrain,  with 
particular  reference  to  its  bearing  on  the  drainage  problem  and 
also  its  general  relation  to  the  surface  of  the  swamp. 

W ell-drained  and  undrained  swamps  compared. — In  their 
typical  development,  well-drained  and  undrained  swamps  differ 
from  one  another  in  several  important  respects.  (1)  Well- 
drained  swamps  are  best  developed  on  springy  slopes,  where  the 
gradiant  is  sufficiently  steep  to  insure  adequate  drainage.  They 
also  commonly  occur  along  the  banks  of  streams  (many  such 
swamps,  more  especially  along  small  brooks,  are  better  included 
with  the  swamps  of  the  inland  group  than  with  those  of  the 
river  group).  Undrained  swamps,  as  exemplified  by  bogs, 


356 


George  E.  Nichols, 


ordinarily  are  best  developed  in  relatively  deep,  undrained  or 
poorly  drained,  water  filled  depressions.  For  reasons  which  will 
be  apparent  later,  however,  in  humid  regions,  like  the  one  under 
discussion,  swamps  of  the  undrained  type  are  by  no  means  con- 
fined to  depressions.  ( 2 ) Both  well-drained  and  undrained 
swamps  may  be  underlain  by  peat ; but  in  the  former  the  deposit 
usually  is  quite  shallow  and  sometimes  it  is  entirely  absent. 
Moreover,  in  well-drained  swamps  the  peat  as  a rule  is  mucky, 
the  plant  remains  being  pretty  thoroughly  decomposed. 
Undrained  swamps  invariably  are  underlain  by  peat  deposits, 
which  often  exceed  fifteen  feet  in  thickness ; the  peat  is  more 
or  less  spongy,  and  the  plant  remains  for  the  most  part  are  well 
preserved.  (3)  The  soil  in  practically  all  swamps  in  northern 
Cape  Breton  is  acid  to  litmus,  but  it  is  appreciably  more  so  in 
swamps  of  the  undrained  type  than  in  others.  (4)  The  vege- 
tation of  well-drained  swamps  is  characterized  by  the  moderate 
abundance  of  the  sphagnums ; by  the  great  variety  of  herbaceous 
seed-plants,  which  in  large  part  are  hydrophytes ; by  the 
scarcity  of  ericaceous  shrubs ; and  by  the  presence  of  several 
deciduous  trees  of  southward  distribution.  The  vegetation  of 
undrained  swamps,  on  the  other  hand,  is  characterized  by  the 
luxuriant  development  of  the  sphagnums ; by  the  comparatively 
small  number  of  species  of  herbaceous  seed-plants,  which  in 
large  part  are  bog  xerophytes ; by  the  abundance  of  ericaceous 
shrubs ; and  by  the  absence  of  practically  all  trees  except  the 
black  spruce  and  tamarack. 


b.  THE  ASSOCIATION-COMPLEXES  OF  WELL-DRAINED  SWAMPS 


Pioneer  association-types. — Among  the  important  pioneers  m 
the  development  of  vegetation  on  springy  or  wet  slopes  are  the 


bryophytes,  notably  the  following 

Marchantia  polymorpha* 
Pellia  epiphylla* 

Pallavicinia  Lyellii * 

Scapania  nemorosa* 


species : 

Sphagnum  squarrosum 
Philonotis  fontana * 

Mnium  punctatum * 
Brachythecium  novae-angliae 


Of  the  herbaceous  vascular  plants,  almost  any  of  the  species 
to  be  listed  later  as  characteristic  of  wet  meadows  may  appear 
at  a very  early  stage  in  the  succession,  but  the  following  list 


Vegetation  of  Northern  Cape  Breton.  357 

includes  the  forms  which,  on  the  whole,  are  more  prominent  as 


pioneers : 

Onoclea  sensibilis* 
Equisetum  sylvaticum 
Glyceria  canadensis 
Glyceria  laxa 
Scirpus  atrocinctns 
Scirpus  rubrotinctus 
Carex  crinita 
Carex  scabrata* 
Carex  stipata 
Juncus  articulatus* 
Juncus  brevicaudatus 


Juncus  effusus 
Iris  versicolor * 

Sagina  procumbens * 

Card  amine  pennsylvanica* 
Drosera  rotundifolia 
Chrysosplenium  americanum* 
Hypericum  canadense 
Epilobium  palustre  ■ 
Lysimachia  terrestris 
Lycopus  americanus 
Mentha  arvensis* 


Association-types  of  open  swamps. — The  luxuriant  growth  of 
the  grasses,  sedges,  and  rushes  may  result  in  the  development 
of  a wet  meadow  association-type,  characterized  by  the  pre- 
dominance of  grass-like  growth-forms  and  the  relative  absence 
of  woody  plants.  During  the  evolution  of  the  wet  meadow,  the 
plant  cover  gradually  becomes  denser,  while  the  nature  of 
the  substratum  may  become  modified  through  the  formation  of 
a layer  of  mucky  peat.  Contemporaneously  with  these  changes, 
many  of  the  pioneer  species  (notably  those  starred  [*]  in  the 
above  lists),  either  disappear  or  else  become  restricted  in  their 
distribution  to  the  more  open,  wetter  habitats.  Others  become 
more  abundant,  and  at  the  same  time  still  other  species  not 
before  represented  may  make  their  appearance.  The  following 
list  includes  various  herbaceous  plants,  which,  in  addition  to 
those  already  mentioned,  and  together,  less  frequently,  with  those 
to  be  given  in  a subsequent  list,  commonly  are  more  or  less 
abundantly  represented  in  open,  well-drained  swamps. 


Aspidium  Thelypteris 
Aspidium  cristatum 
Osmunda  cinnamomea 
Osmunda  regalis 
Agrostis  hyemalis 
Calamagrostis  canadensis 
E rio phorum  virginicum 
Carex  canescens  disjuncta 


Habenaria  dilatata 
Habenaria  psycodes 
Thalictrum  polygamum 
Fragaria  virginiana 
Geum  rivale 
Sanguisorba  canadensis 
Chelone  glabra 
Galium  palustre 


358 


George  E.  Nichols, 


Car  ex  flava 
Carex  intumescens 
Carex  pallescens 
Carex  paupercula 
Carex  stellulata 
Habenaria  clavellata 


Eupatorum  purpureum 
Aster  nemoralis 
Aster  puniceus 
Aster  radula 
Aster  umbellatus 


The  bryophytes,  as  a rule,  are  well  represented  in  open 
swamps,  usually  forming  a more  or  less  conspicuous  understory 
of  vegetation.  The  following  additional  species  may  be  men- 
tioned as  characteristic : 


Sphagnum  palustre 
Sphagnum  imbricatum 
Sphagnum  magellanicum 
Sphagnum  Girgensohnii 


Camptothecium  nitens 
Rhytidiadelphus  squarrosus 
Chrysohypnum  stellatum 
Acrocladium  cuspidatum 


More  often  than  not,  shrubs  put  in  their  appearance  so  early 
that  the  wet-meadow  stage  in  the  succession  is  of  very  brief 
duration.  Frequently  it  is  eliminated  as  a distinct  phase. 
Instead,  there  may  arise  a mixed  growth  of  shrubs  and  herba- 
ceous plants : these  with  scattered  trees  constitute  the  most 
familiar  type  of  vegetation  in  open  swamps.  The  common 
pioneer  shrub  is  the  alder  ( Alnus  incana).  Associated  with  this 
may  grow  any  (or  all)  of  the  following  species: 


Salix  humilis 
Myrica  Gale 
Ribes  hirtellum 
Spiraea  latifolia 
Rubus  pubescens 


Rubus  canadensis 
Rosa  nitida 
Ilex  verticillata 

Viburnum  Opulus  americanum 
Viburnum  cassinoides 


On  the  whole,  ericaceous  shrubs  (or  semi-shrubs)  are  scarce 
in  well-drained  swamps,  but  Chiogenes  hispidula  commonly, 
Kalmia  angustifolia  frequently,  and  Chamaedaphne  calyculata 
and  Vaccinium  macrocarpon  occasionally  are  present. 

The  edaphic  climax  association-type. — Ultimately  the  entire 
swamp  may  become  wooded,  but,  as  a rule,  much  of  it  remains 
fairly  open,  with  trees  scattered,  but  more  abundant  toward  the 
margin,  and  with  the  shrubs  and  herbaceous  plants  of  open 
swamps  occupying  the  spaces  between  them.  The  predominant 
trees,  as  a rule,  are  balsam  fir,  black  spruce,  white  spruce,  and 


Vegetation  of  Northern  Cape  Breton. 


359 


red  maple ; but  associated  with  these,  in  varying  abundance,  may 
grow  paper  birch  and  yellow  birch,  white  ash  and  black  ash 
( Fraxinus  nigra),  and  occasionally  white  pine. 

The  vegetation  of  wooded  swamps  may  include  various  of  the 
herbaceous  and  shrubby  species  already  listed,  but  in  addition  to 
these  a number  of  forms  occur  here  which  have  not  yet  been 
mentioned,  although  some  of  them  may  likewise  grow  in  open 
swamps.  Such,  for  example,  are  the  following: 


Phegopteris  polypodioides 
Aspidium  noveboracense 
Osmunda  Claytoniana 
Taxus  canadensis 
Carex  trisperma 
Carex  tenella 
Carex  leptalea 
Carex  folliculata 
Clintonia  borealis 


Maianthemnm  canadense 
Coptis  trifolia 
Mitella  nuda 
Oxalis  Ac eto sella 
Viola  renifolia 
Circaea  alpina 
Cornus  canadensis 
Linnaea  borealis  americana 
Aster  acuminatus 


C.  THE  ASSOCIATION-COMPLEXES  OF  UNDRAINED  SWAMPS 

Occurrence  of  bogs  along  the  coast. — In  the  vicinity  of  Bad- 
deck  and  in  other  localities  where  the  clayey  nature  of  the  soil 
retards  drainage,  bogs  may  develop  in  shallow  depressions  of 
any  description.  They  develop  best,  however,  here  as  in  regions 
farther  south,  in  fairly  deep,  closed,  water-filled  depressions. 
Raised  bogs,  such  as  occur  along  the  coast  in  New  Brunswick 
(see  Ganong  ’98),  and  which  are  extensively  developed  on  the 
interior  plateau  in  northern  Cape  Breton,  are  apparently  absent 
along  the  coast.  The  finest  series  of  bogs  discovered  in  the  low- 
land is  situated  near  the  mouth  of  the  Barrasois  River,  where  in 
a tract  of  woodland  less  than  a square  mile  in  area  there  are 
six  or  eight  fine  examples.  All  of  these  occupy  closed  basins, 
presumably  kettle  holes  in  the  drift,  but  possibly  drift-covered 
sink  holes,  range  in  size  from  less  than  one  to  more  than  three 
acres,  and  bear  a remarkable  resemblance  to  certain  Connecticut 
bogs  (see  Nichols  ’15,  pp.  202-217).  The  following  observa- 
tions relate  more  particularly  to  this  collection  of  bogs,  which 
can  be  regarded  as  representative. 

The  floating  mat  and  its  association-types. — The  early  stages 
of  bog  development  are  best  exhibited  in  the  largest  of  these 


36° 


George  E.  Nichols, 


bogs,  where,  at  the  south  end,  there  still  remains  a pond  some 
sixty  feet  long  by  twenty-five  feet  wide  (Fig.  43).  The  filling 
in  of  such  a pond  is  accomplished  through  the  intervention  of  a 
floating  mat,  and  the  general  features  of  mat  formation  are  quite 
similar  to  what  the  writer  has  described  for  Connecticut  bogs 
(’15,  pp.  196-202).  Its  formation  is  brought  about  through  the 
combined  activity  of  shrubs,  sedges,  and  sphagnums.  Very 


Figure  43. — Bog  near  mouth  of  Barrasois  River ; Nymphaea  in  fore- 
ground ; sedge-shrub-sphagnum  mat  in  middle  distance ; bog  forest  in 
center  background. 

commonly  the  forerunner  of  mat  formation  is  the  cassandra 
( Chamaedaphne  calyculata) . This  shrub  occurs  both  along  the 
shore  and  along  the  edge  of  the  advancing  mat  and  frequently 
grows  out  several  feet  into  the  open  water.  Its  relation  to  the 
mat  is  similar  to  that  of  the  steel  framework  to  a concrete 
building : it  forms  a skeleton  upon  which  the  sphagnum  may  be 
supported.  The  necessity  for  such  support  will  be  pointed  out 
in  the  next  section.  Where,  as  is  commonly  the  case,  the  cassan- 
dra is  followed  by  a dense  growth  of  sphagnum,  a mat  is 


Vegetation  of  Northern  Cape  Breton.  361 

developed.  Where,  however,  as  along  the  south  shores  of  several 
of  these  bogs,  shade  conditions  preclude  the  growth  of  the 
sphagnums,  no  mat  is  developed  (see  further  on  p.  363).  So 
luxuriant,  as  a rule,  is  the  development  of  the  sphagnums  that 
the  important  role  played  by  the  cassandra  is  liable  to  be  over- 
looked ; but  if  a newly  formed  “sphagnum  mat”  be  dug  into,  the 
woody  ribs  formed  by  this  shrub  will  usually  be  found. 

In  some  instances,  certain  sedges  play  a role  similar  to  that 
just  ascribed  to  the  cassandra.  Certain  of  these,  e.  g.,  Carex 
filiformis,  in  contrast  to  the  shrubs,  are  quite  capable  of  forming 
a mat  themselves,  independently  of  any  assistance  from  the 
sphagnums.  But,  as  a rule,  the  sphagnums  make  their  appear- 
ance at  an  early  stage  in  the  history  of  the  mat  and  thereafter 
pla)r  an  important  part  in  its  development : ordinarily  they 

spread  so  rapidly  and  grow  with  such  luxuriance  as  to  quickly 
become  the  predominant  element  of  the  plant  cover.  Various 
features  associated  with  the  formation  and  growth  of  floating 
mats  are  discussed  further  in  the  following  paragraphs  and  in 
later  pages,  in  connection  with  the  swamps  of  the  highland. 

On  the  “sphagnum  mat”  thus  formed,  in  greater  or  less 
abundance,  grow  various  sedges  and  shrubs  which,  by  their  roots, 
rhizomes  and  trailing  stems,  tend  to  bind  together  and  consoli- 
date the  otherwise  loose  structure.  Characteristic  species  are 
the  following: 

Eriophorum  callitrix 
Eriophorum  virginicum 
Rynchospora  alba 
Carex  canescens  disjuncta 
Carex  paupercula  irrigna 
Carex  stellulata 

Along  the  wet  margin  of  the  mat,  where  it  borders  on  the 
marginal  ditch  (see  further  below),  and  in  the  ditch  itself  where 
this  is  swampy,  commonly  grow  various  forms  which  one 
ordinarily  associates  with  well-drained  swamps ; among  them : 
Sparganium  americcmum,  Iris  versicolor,  Alnus  incana,  Myrica 
Gale,  Rosa  nitida,  Ilex  verticillata,  Hypericum  virginicum, 
Lysimachia  terrestris,  and  Lycopus  americanus.  These  plants 
seldom  occur  in  the  older  parts  of  the  bog. 

Trans.  Conn.  Acad.,  Vol.  XXII  22  1918 


Kalmia  poli folia 
Ledum  groenlandicum 
Vaccinium  macrocarpon 
Vaccinium  Oxycoccus 
Menyanthes  trifoliolata 


362 


George  E.  Nichols, 


The  sphagnums  in  relation  to  the  formation  of  floating  mats. — 
The  relatively  subordinate  role  played  by  the  sphagnums  in 
initiating  the  formation  of  floating  mats  was  suggested  by 
Ganong  (’03,  pp.  440-441)  and  Transeau  (’o5-’o6,  p.  363),  and 
has  been  emphasized  by  Davis  (’07),  Cooper  (T3)  and  others. 
From  these  and  the  writer’s  observations  it  seems  certain  that 
in  general  the  appearance  of  the  sphagnum  is  subsequent  rather 
than  antecedent  with  reference  to  that  of  the  vascular  plants. 
The  inability  of  the  sphagnums  of  themselves  to  form  a mat 
may  be  attributed  largely  to  the  lack  of  coherence  and  buoyancy 
in  the  mass  of  floating  vegetation  which  they  sometimes  form.. 
But  added  to  this  is  the  fact  that  comparatively  few  species  of 
sphagnum  are  capable  of  flourishing  with  their  foliage  completely 
submerged.  Of  course  there  are  certain  sphagnums  which  are  dis- 
tinctly aquatic  in  their  mode  of  growth,  but  among  the  twenty 
species  which  have  been  recorded  from  Cape  Breton,  only 
two  definitely  belong  in  this  category,  namely,  5".  Pylaisei  and 
.S’,  cuspidatum  (see  in  this  connection  the  ecological  classifica- 
tion of  bog  sphagnums  on  p.  422}.  In  many  mountain  ponds  these 
two  species  grow  in  great  profusion,  floating  at  or  just  below  the 
surface  of  the  water,  and  their  ecological  relations  there  will  be 
discussed  in  some  detail  later  (see  especially  pp.  424,  429), 
Neither  of  these  two  species,  however,  occurs  in  any  abundance 
along  the  coast : in  fact,  the  writer  has  never  seen  N.  Pylaisei 
except  in  the  mountains,  while  5".  cuspidatum,  though  frequently 
represented  in  lowland  ponds  by  the  var.  Torreyi,  is  seldom  of 
ecological  importance  here.  The  important  mat  pioneers  among 
the  sphagnums  in  the  Barrasois  bogs,  which  may  be  regarded  as 
representative  of  lowland  bogs  in  general,  are  S',  papillosum,  S. 
magellanicum,  and  S.  recurvum.  These  three  species  grow  best 
in  very  wet  situations,  but  they  will  flourish  only  where  the 
nature  of  the  substratum  is  such  that,  at  least  throughout  most 
of  the  growing  season,  their  shoots  remain  partially  raised  above 
water  level.  The  maintenance  of  this  position  they  are  not  suffi- 
ciently buoyant  to  accomplish  themselves,  so  that  the  pre- 
existence of  some  sort  of  a support  to  prevent  their  sinking 
below  the  surface  is  essential.  Hence  the  importance  of  shrubs 
and  sedges  as  pioneers  in  the  development  of  a “sphagnum  mat.” 
The  marginal  ditch  and  its  significance. — The  formerly  water- 
filled  depressions  now  occupied  by  the  Barrasois  bogs  have 


Vegetation  of  Northern  Cape  Breton. 


36  3 


become  almost  completely  filled  in  through  the  activity  of  vege- 
tation. All  that  remains  in  most  cases  to  remind  one  of  the  pond 
stage  in  the  succession  is  a moat-like  marginal  ditch  or  fosse, 
which  averages  perhaps  ten  feet  in  width  and  up  to  two  or  more 
feet  in  depth,  which  may  be  open  and  filled  with  water  or 
occupied  by  a wet  sphagnous  swamp,  and  which,  as  a rule,  more 
or  less  completely  encircles  the  area  occupied  by  the  bog  proper. 
The  significance  of  this  marginal  ditch  is  not  wholly  clear.  Else- 
where (’15,  pp.  207,  208),  the  writer  has  been  inclined  to  uphold 
the  explanation  first  suggested  by  Davis  (’07,  pp.  150,  151),  which 
attempts  to  correlate  it  with  fluctuations  in  water  level.  But 
conditions  here  in  northern  Cape  Breton  are  even  better  explained 
by  Atkinson’s  theory  (’05,  pp.  615,  616)  that  the  formation  of 
the  ditch  is  due  to  the  shade  produced  by  the  forest  along  the 
shore,  which  hinders  or  prevents  the  growth  of  the  mat-forming 
plants.  In  several  of  the  forest-encircled  Barrasois  bogs  the 
ditch  is  open  along  the  southern  shore,  i.  e.,  along  the  shore  where 
the  effect  of  the  shade  produced  by  the  fringing  forest  naturally 
would  be  most  pronounced,  while  along  the  northern,  least  shaded 
shore  it  has  become  completely  filled  in  by  vegetation.  This 
condition  obviously  cannot  be  explained  by  the  fluctuation  theory ; 
and  for  that  matter,  as  already  mentioned,  there  is  very  little 
seasonal  fluctuation  in  water  level  in  these  basins. 

Development  of  the  edaphic  climax  association-type. — Beyond 
the  wet  bog  stage,  further  development  is  largely  dependent  on 
two  species  of  Sphagnum  which  have  not  as  yet  been  mentioned : 
S.  fuscum  and  S.  capillaceum  tenellum,  particularly  the  former. 
Where  the  hydrophytic  (or  relatively  mesophytic)  pioneer  sphag- 
nums  are  superseded  by  these  relatively  xerophytic  forms,  the 
surface  of  the  bog  may  become  built  up  a foot  or  more  above 
water  level.  In  a mature  bog  the  sphagnums  almost  everywhere 
are  the  predominant  plants  underfoot.  They  cover  the  ground 
with  a continuous,  hummocky,  mattress-like  carpet,  which  con- 
sists for  the  most  part  of  the  russet-green  6’.  fuscum,  interspersed 
with  occasional  more  or  less  extensive  patches  of  the  reddish  S. 
capillaceum  tenellum.  Commonly  growing  along  with  the 
sphagnums,  in  the  older  parts  of  the  bog,  are  two  mosses : 
Polytrichum  commune  and  P.  juniperinum,  while  in  some  of  the 
higher,  drier  areas  the  sphagnums  may  have  become  superseded 
by  cladonias  or  by  such  bryophytes  as  Ptilidium  ciliare  and 


364 


George  E.  Nichols, 


Hypnum  Schrebcri.  Here  and  there,  even  in  an  old  bog,  there 
are  moist  or  wet  depressions  in  which  may  occur  the  more  hydro- 
phytic  species  of  Sphagnum,  together  with  liverworts  such  as 
Ceplialozia  fluitans  and  Mylia  anomala  and  mosses  such  as 
Calliergon  stramineum  and  Drepanocladus  fluitans. 

Scattered  about  over  the  sphagnum  substratum,  and  varying 
greatly  in  abundance  locally,  are  diverse  trees,  shrubs,  and  herba- 
ceous plants.  The  characteristic  and  omnipresent  tree  of  bogs 
is  the  black  spruce.  Invariably  dwarfed  in  size,  it  commonly 
forms  low,  scraggly  clumps,  the  result  of  layering  followed  by 
the  death  of  the  parent  tree  or  of  the  original  trunk.11 

The  predominant  bog  shrubs  are  ericads : Chamaedaphne 

calyculata , Gaylussacia  baccata,  Kalmia  angustifolia,  K.  polifolia, 
and  Ledum  groenlandicum,  to  which  should  be  added  the  semi- 
shrubby  forms,  Chio genes  hispidula  and  Vaccinium  Oxycoccus. 
Three  non-ericaceous  shrubs  also  are  usually  well  represented : 
Amelanchier  sp.,  Nemopanthus  mucronata,  and  Viburnum  cas- 
sinoides.  The  most  important  herbaceous  species  are  Osmunda 
cinnamomea,  Eriophorum  callitrix,  E.  virginicum,  Rynchospora 
alba,  Carex  trisperma  Billingsii,  and  Cornus  canadensis.  Three 
orchids,  Habenaria  blephariglottis,  Pogonia  ophioglossoides,  and 
Calopogon  pulchellus,  are  conspicuous  when  in  flower;  Drosera 
rotundifolia  is  common,  and  Lycopodium  inundatum  occasional 
in  moist  depressions ; Smilacina  trifolia  occurs  locally  in  wet 
places  ; Empetrum  nigrum  grows  abundantly  in  the  drier  portions 
of  one  bog;  while  Arceuthobium  pusillum  is  a frequent  parasite 
on  the  black  spruce. 

d.  THE  ASSOCIATION-COMPLEXES  OF  POORLY  DRAINED-  SWAMPS 

Under  the  head  of  poorly-drained  swamps  are  classed  swamps 
of  an  intermediate  character : swamps  whose  vegetation  resembles 
in  some  respects  that  of  well-drained  swamps,  in  other  respects 
that  of  undrained  swamps.  Boggy  swamps  of  this  character 
are  of  far  more  general  occurrence  than  are  those  of  the  more 
extreme  types,  such  as  have  been  described  in  the  foregoing 
paragraphs. 

11  Ganong  (’9 7:  see  quotation  on  p.  447  of  the  present  paper)  has 

called  attention  to  layering  as  a means  of  reproduction  in  Picea  mariana, 
and  the  phenomenon  has  been  discussed  in  some  detail  by  Cooper  (’11) 
and  Fuller  (’13). 


Vegetation  of  Northern  Cape  Breton.  365 

Illustrative  examples. — The  general  situation  in  poorly  drained 
swamps  is  unusually  well  illustrated  by  a group  of  small  swamps 
on  Broadcove  Mountain,  which  were  studied  in  some  detail. 
These  swamps  occupy  a series  of  very  shallow,  trough-like  depres- 
sions, which  cross  approximately  at  right  angles  the  road  from 
Ingonish  to  Neil’s  Harbor.  Three  of  them,  which  may  be 
designated  respectively  as  swamps  A,  B,  and  C,  are  roughly 
represented  in  longitudinal  section  in  Fig.  44.  The  surface 
slope,  depth  of  peat,  etc.,  were  determined  by  means  of  sounding- 
rod  and  level.  All  three  swamps  have  outlets  at  the  lower  end, 
and  swamp  A has  a small  brooklet  traversing  perhaps  half  its 
length.  At  the  time  they  were  studied  (August,  1916),  the  out- 


Figure  44. — Diagrammatic  longi-sections  of  poorly  drained  swamps  on 
Broadcove  Mountain,  north  of  Ingonish:  see  text. 


lets  in  swamps  B and  C were  dry,  but  a small  amount  of  water 
was  trickling  out  of  A. 

Swamp  A. — This  swamp  is  the  least  boggy  of  the  three. 
Genetically  it  represents  a condition  which  presumably  obtained 
at  an  earlier  period  in  the  development  of  swamp  B.  In  area  it 
is  about  300  feet  long  by  100  feet  wide.  In  proceeding  from  its 
upper  to  its  lower  end,  the  ground  slopes  gently,  dropping  at  the 
rate  of  about  1 : 50.  Over  almost  the  entire  tract  a layer  of 
peat  from  two  to  two  and  a half  feet  in  thickness  has  been  formed. 
The  aspect  of  the  vegetation  over  much  of  the  area  is  that  of  a 
meadow : Scirpus  hudsonianus  and  S',  caespitosus  with  species  of 
Sphagnum  form  the  bulk  of  the  plant  cover.  Scattered  over  the 
meadow  are  various  herbaceous  plants,  shrubs,  and  trees, 
Osmunda  regalis  in  particular  of  the  herbs  forming  considerable 


366 


George  E.  Nichols, 


patches  locally.  Along  the  margin  of  the  swamp  is  a fringe  of 
swamp  forest.  Floristically  the  vegetation  of  this  swamp 
resembles  in  many  respects  that  of  an  ordinary  well-drained 
swamp.  The  majority  of  the  vascular  plants  present  there  are 
also  represented  here,  but  they  are  relatively  much  less  abundant. 
Myrica  Gale  is  perhaps  the  commonest  shrub  in  the  open  part  of 
the  swamp,  and  there  are  present  here  three  shrubs  not  previously 
listed:  Pyrus  arbutifolia  atropurpurea,  Rhamnus  alnifolia,  and 
Lonicera  caerulea.  The  boggy  nature  of  the  swamp  is  suggested 
by  the  presence  of  such  plants  as  the  two  species  of  Scirpus 
mentioned,  Rynchospora  alba,  Smilacina  trifolia,  Sarracenia 
purpurea,  Vaccinium  Oxycoccus,  and  Lobelia  Kalmii,  as  well  as 
by  the  luxuriant  growth  of  the  sphagnums.  The  dissimilarity 
between  this  swamp  and  a bog  is  emphasized,  among  other  things, 
by  the  presence  among  the  marginal  woody  forms  of  Taxus 
canadensis,  Acer  rubrum,  Fraxinus  americana  and  F.  nigra. 

Viewed  from  a genetic  standpoint,  it  seems  apparent  that  the 
area  formerly  occupied  by  the  swamp  vegetation  was  much  more 
restricted  than  that  which  it  occupies  to-day.  Originally  long 
and  narrow,  as  the  surface  has  become  built  up  through  the 
accumulation  of  peat  the  swamp  has  spread  out  laterally, 
encroaching  on  the  adjoining  forested  areas.  Evidences  of  quite 
recent  encroachment  were  noted  just  above  where  the  swamp 
crosses  the  road.  Among  the  pioneer  seed  plants,  to  judge  from 
a relict  colony  near  the  lower  end  of  the  swamp,  were  Calama- 
grostis  canadensis,  Juncus  brevicaudatus,  and  Iris  versicolor;  but 
the  upbuilding  of  the  surface  and  the  lateral  expansion  of  the 
swamp  have  been  largely  attributable  to  the  luxuriant  growth  of 
the  sphagnums  and  of  the  two  sedges,  Scirpus  hudsonianus  and 
.S’,  caespitosus.  It  may  well  be  said  that  the  nature,  and  indeed 
the  very  existence,  of  the  swamp  as  it  is  to-day  is  closely 
correlated  with  the  activity  of  the  compact  mass  of  peat  thus 
formed  and  of  the  superimposed  plant  cover  in  obstructing  the 
drainage  and  thereby  conserving  the  water  supply. 

Swamps  B and  C. — Swamp  B,  from  a genetic  standpoint,  may 
be  regarded  as  representing  a later  stage  in  the  developmental 
series  than  swamp  A.  Conditions  in  swamp  B have  been  more 
favorable  to  peat  accumulation  than  in  swamp  A,  owing  to  the 
more  level  nature  of  the  terrain,  and  over  much  of  the  area  the 
deposit  of  peat  is  more  than  six  feet  thick.  It  will  be  noted 


Vegetation  of  Northern  Cape  Breton. 


367 


(toward  the  right  in  Fig.  44)  that  where  the  rock  floor  is 
slightly  inclined  the  layer  of  peat  becomes  thinner.  Swamp  C 
differs  from  both  swamps  A and  B in  having  originated  in  and 
around  a shallow,  poorly  drained  pond,  the  extreme  depth  of 
which  was  not  ascertained.  In  its  larger  aspects,  the  vegetation 
in  both  these  swamps  is  similar  to  that  of  swamp  A:  the  two 
species  of  Scirpns  and  the  Sphagna  predominate,  and  various 
species  characteristic  of  both  well-drained  and  undrained  swamps 
are  represented.  But  the  still  more  boggy  nature  of  the  habitat 
is  evidenced  particularly  by  the  frequency  here  of  the  ericaceous 
shrubs,  Chamaedaphne  calyculata  and  Ledum  groenlandicum, 
neither  of  which  occur  in  swamp  A.  The  relatively  xerophytic 
nature  of  the  habitat  is  further  suggested  by  the  presence  of 
Pteris  aquilina  and  Juniperus  communis  depressa. 

The  following  list  of  species  characteristic  of  one  or  all  of  the 
Broadcove  Mountain  swamps,  but  mostly  not  heretofore  men- 
tioned in  any  connection,  is  of  interest. 


S elaginella  selaginoides 
Larix  laricina 
Muhlenbergia  racentosa 
Eriophorum  tenellum 
Eriophorum  viride-carinatum 
Car  ex  Michauxiana 
Carex  oligosperma 


Spiranthes  Romansoffiana 
Potentilla  fruticosa 
Viola  conspersa 
Conioselinum  chinense 
Solidago  rugosa 
Solidago  uliginosa 
Cirsium  muticum 


General  observations. — In  general,  bogginess  seems  to  be 
correlated  with  poor  drainage ; and  this  may  be  either  occasioned 
by  the  nature  of  the  terrain  or  brought  about  through  the 
influence  of  vegetation.  Topography  favors  the  development  of 
boggy  swamps  where  the  surface  is  flat,  fairly  level,  and  so 
situated  that  the  ground  becomes  covered  with  a thin  sheet 
of  water  in  wet  weather.  Boggy  swamps  are  frequently 
encountered,  for  example,  on  low,  flat  areas,  bordering  lakes  and 
ponds,  which  are  subject  to  periodic  inundation  (see  in  this  con- 
nection p.  419).  A heavy  soil  which  dries  out  slowly  favors  the 
development  of  boggy  swamps.  But  many  of  the  tracts,  which 
in  northern  Cape  Breton  are  occupied  by  swamps  of  this  type,  in 
a warmer,  less  humid  climate  would  be  merely  periodic  swamps 
of  the  ordinary,  well-drained  type.  The  general  prevalence  here 


368 


George  E.  Nichols, 


of  boggy  swamps  may  be  attributed  in  large  measure,  indirectly, 
to  the  influence  of  the  cool,  humid  climate  of  the  region. 
The  climate  favors  the  luxuriant  development  of  the  sphagnums 
and  other  peat-forming  plants,  and  it  seems  to  be  very  largely 
through  the  direct  influence  of  the  layer  of  peat  to  which  these 
give  rise,  in  retaining  the  water  and  thereby  extending  the 
swampy  condition  throughout  the  season,  that  the  boggy  condi- 
tion is  brought  about.  Very  often,  in  this  way,  through  the 
obstruction  of  the  drainage  which  results  from  the  activity  of 
the  vegetation,  a swamp  which,  during  the  early  stages  of  its 
development,  would  be  classed  as  well-drained,  in  the  course  of 
time  becomes  increasingly  boggy.  This  is  well  illustrated  by  the 
examples  just  described. 

It  has  been  mentioned  earlier  that  peat  accumulation  may  occur 
in  connection  with  well-drained  swamps ; but  there,  as  already 
suggested,  the  deposit  is  mucky  and  invariably  shallow.  Again, 
the  bog  has  been  cited  as  the  characteristic  swamp-type  of 
undrained  depressions ; but  not  infrequently  shallow,  undrained 
depressions  are  occupied  by  swamps  of  the  poorly  drained  type. 
Sink  hole  swamps  are  often  of  this  character.  Fluctuations  in 
water  level,  underground  drainage,  alkalinity  of  the  soil  water, 
or  some  such  factors  may  perhaps  explain  the  discrepancy  here. 
But,  after  all,  the  whole  swamp  situation  is  an  extremely  com- 
plex one,  and  it  is  candidly  admitted  that  there  are  any  number 
of  questions  which  must  be  left  unanswered. 


4.  The  formation-types  in  and  along  Rivers  and  Streams 

a.  INTRODUCTORY 

Under  this  head  are  included  fundamentally  those  association- 
complexes  of  hydrarch  origin  whose  ecological  aspect  manifestly 
is  correlated  with  the  activity  of  rivers  and  streams.  In  so  far 
as  it  affects  associations  of  the  hydrarch  series,  the  influence  of 
a stream  on  the  vegetation  in  and  along  its  course  is  expressed 
primarily  at  times  of  high  water,  and  then  in  two  ways : first, 
through  the  deposition  of  sediment,  which  leads  to  the  develop- 
ment of  flood  plains ; second,  through  the  erosive  activity  of 
the  current,  which  may  affect  the  vegetation  directly,  particularly 
through  the  abrading  action  of  ice,  or  indirectly,  as  seen  in  the 
formation  of  oxbows.  Under  this  head  have  also  been  included 


Vegetation  of  Northern  Cape  Breton.  369 

the  association-complexes  of  wet  or  dripping  rock  outcrops, 
since  these  are  especially  characteristic  of,  though  by  no  means 
confined  to,  ravines. 

b.  THE  ASSOCIATION-COMPLEXES  OF  RAVINES 

The  stream  bed  association-types. — The  predominant  plants  in 
the  rocky  stream  beds  which  prevail  in  ravines,  and  to  a large 
extent  elsewhere,  are  bryophytes.  Characteristic  species  are  the 
following: 

Marsupella  aqnatica 
Jungermannia  cordi folia 
Scapania  undulata 
Porella  pinnata 
Fontinalis  dalecarlica 

The  degree  of  luxuriance  exhibited  by  the  submersed 
bryophytic  vegetation  varies  greatly  in  different  streams.  The 
aquatic  mosses  and  liverworts  are  best  developed  in  small  brooks ; 
in  large  streams  they  may  be  conspicuous  by  their  absence. 
This  latter  fact  may  be  explained  somewhat  as  follows.  The 
instability  of  the  substratum  might  account  for  their  absence  on 
small  boulders  and  cobbles,  but  even  where  there  is  a firm  rock 
substratum,  bryophytes  are  scarce.  There  seems  little  question 
that,  in  general,  the  scarcity  is  attributable  to  mechanical  factors 
— to  the  erosive  action  of  the  sediment-laden  water  in  flood  time, 
or,  more  likely,  of  ice-laden  water  in  spring.  Were  the 
phenomenon  restricted  to  northern  Cape  Breton,  one  might  feel 
tempted  to  correlate  it  with  the  acidity  of  the  water,  which  in 
most  streams  commonly  contains  so  much  organic  matter  that 
it  is  colored  yellow  or  brownish  (see,  in  this  connection,  Ganong 
’98)  ; but  the  same  conditions  can  be  observed  in  other  regions, 
e.  g.,  in  Connecticut  streams,  where  the  water  is  clear  and  color- 
less. Often  the  rocky  bottom  in  swift  streams  is  utterly  devoid 
of  plants  of  any  description,  but  sometimes,  in  the  absence  of 
mosses,  there  may  be  a considerable  growth  of  Nitella  sp. 

Stream  bank  association-types. — Along  small  ravine  brooks 
the  banks,  as  a rule,  are  well  shaded  by  overhanging  foliage, 
the  air  is  always  cool  and  moist,  and  the  substratum  con- 
tinuously damp  or  wet.  It  is  doubtful  whether  the  plant  cover 


O xyrrhynchium  rusciforme 
Hygrohypnum  dilatatum 
Hygrophynum  eugyrium 
Hygrophynum  ochraceum 


37° 


George  E.  Nichols, 


in  many  such  habitats  ever  has  been  xerophytic,  and  for  this 
reason  it  has  seemed  best  to  treat  it  under  the  head  of  hydrarch 
successions.  The  outstanding  feature  of  such  a ravine  is  the 
intense  mesophytism,  commonly  verging  on  hydrophytism,  of  its 
vegetation.  In  the  periodically  inundated  zone  along  the  edge 
of  the  stream  there  is  a profuse  development  of  mosses  and 
liverworts,  which  commonly  include,  among  others,  the  follow- 
ing species : 


Conocephalum  conicum 
Plagiochila  asplenioides 
Sphagnum  squarrosum 
Fissidens  adiantoides 
Mnium  hornum 
Mnium  punctatum 


Philonotis  fontana 
Thuidium  delicatulum 
B r achy  the  cium  rivulare 
Hylocomium  brevirostre 
Climacium  dendroides 
Catharinaea  undulata 


Vascular  plants  are  more  or  less  numerous,  particularly 
toward  the  upper  limit  of  the  flood  zone.  Here  the  ferns  are 
represented  by  a wealth  of  species,  among  which  P olystichum 
Braunii  is  especially  characteristic,  while  the  seed  plants  include 
some  of  the  most  pronounced  shade-  and  moisture-loving 
mesophytes.  A list  of  some  of  the  more  representative  ferns 
and  seed  plants  follows  : 


Phegopteris  polypodioides 
Phegopteris  Dryopteris 
Asplenium  Filix-femina 
Polystichum  acrostichoides 
P olystichum  Braunii 
Aspidium  noveboracense 


Aspidium  spimdosum  var. 
.S’ treptopus  amplexifolius 
Geum  macro phyllittm 
Circaea  alpina 
Galium  kamtschaticmn 
Aster  acuminatus 


Along  the  larger  ravine  streams  the  banks  are  more  exposed 
to  sun  and  wind  than  along  the  smaller  ones,  and  the  vegetation 
tends  to  be  less  mesophytic,  with  shade  plants  in  particular  much 
less  prominent.  The  character  of  the  vegetation  between  low 
and  high  water  levels  is  influenced  to  a more  marked  degree  by 
the  abrading  action  of  the  current  in  flood  time.  Even  here, 
however,  associations  of  the  sort  just  described  are  frequently 
encountered. 

Cliff  association-types. — Many  cliffs  and  steep  rock  outcrops 
are  kept  wet  to  such  a degree  with  dripping  water  that  their 


Vegetation  of  Northern  Cape  Breton.  371 

vegetation  differs  quite  perceptibly  from  that  of  the  drier  cliffs 
described  earlier  under  the  xerarch  series.  It  is  of  course  diffi- 
cult to  draw  sharp  lines,  since  there  are  all  degrees  of  intergrada- 
tion. Here,  as  there,  the  most  distinctive  plants  are  the 
bryophytes,  which  thrive  in  crevices  and  frequently  plaster  over 
even  precipitous  rock  surfaces.  But  in  addition  to  various 
of  the  species  cited  earlier  as  characteristic  of  relatively  dry 
cliffs,  there  occur  here,  usually  as  the  predominant  forms,  various 
more  or  less  hydrophytic  species.  Prominent  among  these  are 
the  sphagnums,  the  species  mainly  those  mentioned  elsewhere  in 
connection  with  the  ravine  forest,  and  the  liverworts  and  mosses 
enumerated  in  the  subjoined  list. 

Marsupella  emarginata 
S phenolobus  Michauxii 
Mylia  Taylor i 
Plagiochila  asplenioides 
Diplophyllum  albicans 
Scapania  nemorosa 
Blindia  acuta 

C.  THE  ASSOCIATION-COMPLEXES  OF  FLOOD  PLAINS 

Here  should  be  included  the  strips  of  swale  which  not  infre- 
quently border  even  rapid  streams  and  which  obviously  represent 
incipient  flood  plains.  In  valleys,  for  example,  and  locally  even 
in  ravines,  a narrow,  marshy  strip  frequently  intervenes  between 
ordinary  summer  water  level  and  the  lower  edge  of  the  upland 
forest.  The  vegetation  in  such  a tract  is  essentially  that  of  a 
well-drained  swamp,  with  sedges,  such  species  as  Carex  torta 
and  C.  aquatilis,  and  the  grass,  Calamagrostis  canadensis, 
usually  the  predominant  forms.  Swampy  flood  plains  of  this 
particular  sort  are  much  more  extensively  developed  on  the 
plateau  (see  p.  456)  than  in  the  lowland,  where  they  are  of 
minor  consequence. 

Of  much  more  importance  here,  though  somewhat  restricted 
in  their  occurrence,  are  the  flood  plain  formations  which  have 
been  developed  in  particular  at  the  mouths  of  some  of  the  larger 
streams,  as  at  the  heads  of  Ingonish  Harbor,  Middle  Harbor 
(Aspy  Bay),  and  Margaree  Harbor.  The  earlier  phases  of  the 
hydrarch  series  of  association-types,  which  reaches  its  culmina- 


Didymodon  rubellus 
Hymeno stylium  curvirostre 
Anoectangium  M ougeotii 
Plagiothecium  denticulatum 
Hylocomium  brevirostre 
Plagiopus  Oederi 


372 


George  E.  Nichols, 


tion  in  the  flood  plain  forests  that  have  been  developed  on  the 
higher  portions  of  flood  plains,  are  well  illustrated  by  the  condi- 
tions about  the  head  of  Margaree  Harbor,  which  will  be  briefly 
described. 

Pioneer  association-types. — Owing  to  the  intermittent  backing 
up  of  the  outflowing  river  water  by  the  inflowing  tide  water, 
the  depth  of  the  water  over  the  submerged  portion  of  the  flood 
plain  here  fluctuates  daily.  On  parts  which  are  permanently 
submerged,  vegetation,  where  present,  consists  largely  of  sub- 
mersed aquatics,  notably  Potamogeton  bupleuroides.  Areas 
which  are  bared  at  low  tide,  but  which  may  be  inundated  to  a 
depth  of  from  perhaps  six  inches  to  two  feet  at  high  tide,  are 
occupied  by  a wet  marsh  association-type,  in  which  the  following 
are  the  more  prominent  species  : 


Equisetum  fluviatile 
Scirpus  occidentals 
Dulichium  arundinaceum 
Typha  latifolia 
Sagittaria  latifolia 


Acorus  Calamus 
Cast  alia  odor  at  a 
Nymphaea  advena 
Cicnta  bulbifera 
Shim  cicutae folium 


Fringing  the  shoreward  margin  of  this  marshy  area  is  a more 
or  less  well  defined  transition  zone,  in  which  the  predominant 
plants  are  species  of  generally  recognized  amphibious  proclivities. 
Here,  to  a greater  extent  than  in  the  areas  of  deeper  water, 
grow,  among  others,  the  following  species : 

Proserpinaca  palustris 
Lysimachia  terrestris 
Menyanthes  trifoliolata 
Myosotis  laxa 
Mentha  arvensis 


Leerzia  oryzoides 
Juncus  brevicandatus 
Iris  versicolor 
Caltha  palustris 
Rumex  Britannica 
Potentilla  palustris 


On  portions  of  the  flood  plain  where  the  water  at  high  tide 
ordinarily  is  very  shallow,  or  which  are  flooded  only  in  time  of 
spring  tides,  the  general  aspect  of  the  association-type  is  that 
of  wet  meadow,  although  various  of  the  marsh  species  may  grow 
here  also.  Below  is  a list  of  some  of  the  species  noted  as 
characteristic  : 


Vegetation  of  Northern  Cape  Breton. 


373 


Acrocladiitm  cuspidatum 
Onoclea  sensibilis 
Aspidium  Thelypteris 
Glyceria  grandis 
Calamagrostis  canadensis 
Carex  crinita 
Habenaria  dilatata 


Sangnisorba  canadensis 
Impatiens  fulva 
Viola  cucullata 
Scutellaria  galericulata 
Chelone  glabra 
Eupatorium  purpureum 
Aster  novi-belgii 


The  edaphic  climax  association-type. — The  condition  of  the 
vegetation  on  parts  of  flood  plains  which  lie  above  ordinary  high 
tide  level  has  been  greatly  modified  by  human  activity,  owing  to 
the  suitability  of  such  areas  for  raising  hay,  and  the  original 
character  of  the  vegetation  here  must  be  judged  from  the 
fragmentary  evidence  which  has  survived. 

In  wet  meadows  of  the  sort  above  described,  the  com- 
mon occurrence  of  scattered  shrubs,  such  as  Alnus  incana 
and  Myrica  Gale,  suggests  that  the  present  day  meadow 
association-type  is  of  secondary  origin ; and  it  is  cer- 
tain, from  the  conditions  observed  at  Margaree  Harbor, 
Ingonish,  and  Aspy  Bay,  that  in  former  days  the  higher  parts 
of  flood-plains  of  the  sort  under  consideration  were  occupied 
by  forests  made  up  largely  of  elm,  white  ash,  black  ash,  and 
white  spruce.  Specimens  of  elm  more  than  six  feet  in  diameter 
are  occasionally  encountered  on  flood  plains.  The  characteristic 
shrubs  here  include  Salix  sp.,  Alnus  incana,  Cornus  stolonifera, 
Viburnum  Opulus  americanum,  and  Sambucus  canadensis. 
Below  is  a list  of  the  more  distinctive  herbaceous  species  of  the 
higher  parts  of  flood  plains,  most  of  them  being  noted  in  all 
three  localities  cited. 


Onoclea  Struthiopteris 
Onoclea  sensibilis 
Asplenium  Filix-femina 
Calamagrostis  canadensis 
Laportea  canadensis 
Thalictrum  polygamum 
Clematis  virginiana 
Agrimonia  striata 
Sangnisorba  canadensis 
Impatiens  bi flora 


Circaea  intermedia 
Heracleum  lanatum 
Galium  asprellnm 
Eupatorium  purpureum 
Solidago  canadensis 
Solidago  rugosa 
Aster  novi-belgii 
Aster  puniceus 
Aster  umbellatus 


374 


George  E.  Nichols, 


The  association-types  of  oxbow  ponds. — Oxbow  ponds  have 
been  observed  in  a few  places,  as  at  Margaree  Harbor  and 
Pleasant  Bay.  Such  ponds  usually  support  a luxuriant  aquatic 
vegetation,  notably  such  species  as  the  following: 

Sparganium  an  git  sti folium  Ranunculus  aquatilis  capillaceus 
Potamogeton  bupleuroides  Callitriche  palustris 

Potamogeton  epihydrus  Ludvigia  palustris 

Scirpus  subterminalis  Myriophyllum  verticillatum 

Nymphaea  advena  Utricularia  intermedia 

Nymphaea  micro phylla  Utricularia  vulgaris 

Castalia  odorata 

The  marginal  vegetation  here  requires  no  particular  comment. 
It  may  include  any  of  the  wet  marsh  species  of  the  flood  plain 
series,  in  addition  to  various  of  the  herbaceous  plants  and  shrubs 
elsewhere  listed  as  characteristic  of  well-drained  swamps. 


4.  The  Formation-types  along  the  Seacoast 

a.  INTRODUCTORY 

In  this  group  may  be  included  all  association-complexes  of 
hydrarch  origin  whose  ecological  aspect  is  influenced  directly  by 
the  proximity  of  the  sea.  This  influence  is  seen  most  obviously 
in  the  effect  of  salt  water  on  the  character  of  the  vegetation. 
But  beside  this,  from  the  standpoint  of  physiographic  ecology, 
the  dynamic  agencies  which  are  associated  with  the  activity  of 
waves  and  currents  are  of  prime  importance,  either  directly  or 
indirectly : the  formation  and  destruction  of  barrier  beaches, 
which  may  result  in  the  development  of  coastal  ponds  of  all 
degrees  of  salinity — from  completely  salt  to  completely  fresh; 
the  deposition  of  sediment,  which  under  favorable  conditions 
may  lead  to  the  development  of  coastal  swamps,  etc.  With 
reference  to  these  physiographic  agencies,  just  as  was  pointed 
out  in  discussing  the  vegetation  of  uplands  along  the  seacoast, 
it  is  possible  to  divide  the  associations  of  lakes  and  swamps  here 
into  two  groups : associations  along  eroding  shores,  and  associa- 
tions along  depositing  shores.  Little  attention  has  been  given, 
however,  to  the  associations  of  the  first  group,  which  comprise 
primarily  the  formation  (or  formation-complex)  of  seaweeds 


Vegetation  of  Northern  Cape  Breton.  375 

concerning  which  brief  mention  has  already  been  made  in  dis- 
cussing the  vegetation  of  rocky  sea  bluffs.  In  the  remarks  which 
follow,  attention  is  restricted  to  the  associations  along  depositing 
shores.  These  are  conveniently  treated  under  three  heads : the 
association-complexes  of  salt  and  brackish  lakes  and  ponds,  the 
association-complexes  of  salt  marshes,  and  the  association- 
complexes  of  brackish  marshes. 

b.  THE  ASSOCIATION-COMPLEXES  OF  SALT  AND  BRACKISH  LAKES 

AND  PONDS 

The  most  prominent  constituent  of  the  aquatic  flora  in  salt 
lakes  and  ponds  is  the  eel  grass  ( Zostera  marina)  which  com- 
monly grows  in  great  luxuriance,  covering  large  areas  of  bottom 
between  approximately  mean  low  water  mark  and  a depth  of 
several  feet  below.  Ecologically  the  eel  grass  fulfils  an  impor- 
tant function  in  that,  by  its  interference  with  tidal  currents,  it 
stimulates  the  deposition  of  silt  and  the  consequent  upbuilding 
of  the  bottom.  Associated  with  the  eel  grass,  but  seldom  attain- 
ing any  great  prominence,  usually  grow  the  sea  lettuce  (JJlva  sp.) 
and  other  algae,  which  may  either  form  a loose  covering  over 
the  sandy  or  muddy  bottom  or  grow  attached  to  the  eel  grass. 
Another  seed  plant  found  here  is  Ruppia  maritima.  In  Middle 
Harbor  (Aspy  Bay),  to  select  a concrete  example,  this  plant  is 
not  at  all  conspicuous  toward  the  outlet,  but  in  the  shallow 
water  about  the  head  of  the  harbor,  in  company  with  Potamoge- 
ton  pectinatns,  it  completely  covers  the  muddy  bottom  with  a 
prolific  growth.  The  presence  here  at  the  head  of  a sizeable 
stream  may  account  for  the  abundance  of  the  Ruppia  in  this 
vicinity,  although  this  plant  is  by  no  means  confined  to  brackish 
water.  In  Cold  Spring  Harbor,  Johnson  (’15,  p.  26)  says  that 
Ruppia  is  most  abundant  in  areas  of  “soft  bottom,  bare  of  TJlva, 
and  usually  protected  from  currents  and  waves.”  It  is  worthy 
of  note,  however,  that  in  brackish  ponds,  in  northern  Cape 
Breton,  the  bulk  of  the  aquatic  vegetation  consists  of  Ruppia 
and  Potamogeton  pectinatus. 

The  shores  of  salt  and  brackish  ponds  may  be  occupied  by  the 
salt  or  brackish  marshes  which  will  be  described  presently,  or 
they  may  be  merely  muddy  or  gravelly.  Gravelly  shores  ordi- 
narily occur  in  moue  exposed  situations  than  muddy  shores.  The 
conditions  which  prevail  on  gravelly  shores  may  be  illustrated 


376 


George  E.  Nichols, 


by  a specific  example,  a spot  just  inside  the  entrance  of  a salt 
pond.  A luxuriant  growth  of  Plantago  decipiens , Spergularia 
leiosperma,  and  Salicornia  europaea  covers  much  of  the  shore 
between  mean  high  and  low  water  levels.  Attached  to  scattered 
cobbles  in  this  zone  are  Fucus,  Ascophyllum,  and  other  algae. 
In  the  vicinity  of  high  water  mark  grow  Puccinellia  maritima , 
Suaeda  maritima , Solidago  sempervirens  and  other  halophytes. 
Such  a shore  may  be  regarded  as  an  incipient  marsh. 

The  vegetation  of  muddy  shores  is  essentially  that  of  the 
marshes.  The  conditions  here  are  well  exemplified  by  a small 
brackish  pond  near  the  Barrasois,  which  has  become  completely 
barricaded  off  from  the  ocean  but  is  still  influenced  by  tide  water 
filtering  through  the  barrier.  The  pond  itself  is  densely  popu- 
lated by  Ruppia  and  Potamogeton  pectinatus,  together  with 
various  algae.  Surrounding  the  pond  is  a low,  muddy  border 
from  two  to  five  feet  wide,  which  is  ordinarily  submerged  at 
high  tide.  The  predominant  plant  here  is  Scirpus  nanus,  which 
forms  a low,  soft  sward.  Associated  with  it  grow  Triglochin 
maritima,  Ranunculus  Cymbalaria,  Spergularia  canadensis,  and 
Salicornia.  At  a slightly  higher  level,  barely  covered  at  ordinary 
high  water,  is  a narrow  zone  of  Spartina  patens,  together  with 
Agrostis  alba  maritima,  Carex  norvegica,  and  Triglochin ; while 
at  a still  higher  level,  not  submerged  by  ordinary  tides,  is  a zone 
occupied  almost  exclusively  by  Juncus  balticus  littoralis.  Such 
an  association-complex,  like  the  preceding,  might  equally  well, 
if  not  better,  be  considered  in  connection  with  salt  and  brackish 
marshes. 

C.  THE  ASSOCIATION-COMPLEXES  OF  SALT  MARSHES 

As  might  be  anticipated,  in  view  of  its  exposed  coastline, 
coastal  swamps  are  nowhere  extensively  developed  in  northern 
Cape  Breton.  The  finest  area  of  this  sort  which  has  come  to 
the  writer’s  attention  is  situated  along  the  oceanward  shore  of 
South  Pond  (Aspy  Bay),  bordering  the  pondward  side  of  the 
sand-spit  elsewhere  described,  and  extending  out  into  the  salt 
pond  nearly  a quarter  of  a mile  (Fig.  45).  This  particular  salt 
marsh  is  of  unique  interest  because  of  the  presence  here  in  situ 
of  a number  of  large  white  pine  stumps.  These  occur  scattered 
throughout  the  landward  half  of  the  marsh  and  their  roots  are 


Vegetation  of  Northern  Cape  Breton. 


377 


well  exposed  above  its  surface.  The  explanation  for  this  unusual 
condition  seems  to  be  this.  The  pines  formerly  grew  on  a low, 
sandy,  pondward  extension  of  the  present  spit.  Through  some 
shifting  in  the  tidal  currents  the  sand  was  eroded  away  from 
around  the  bases  of  the  trees,  and  subsequently,  presumably 
as  the  result  of  further  shifting  in  the  current,  deposition  has 
succeeded  erosion  and  the  salt  marsh  has  been  built  up.  The 
active  erosion  of  the  sand  spit  which  is  now  taking  place  along 


Figure  45. — Salt  marsh  at  South  Pond,  Aspy  Bay;  scattered  stumps  in 
marsh ; see  text. 


certain  other  sections  of  the  shore  upholds  the  plausibility  of 
the  explanation  just  given,  and  excavation  of  the  muddy  deposit 
about  the  stumps  shows  beach-sand  at  a depth  of  scarcely  a 
foot  below  mean  low  tide  level  (in  this  connection,  see  also 
Harvey  T8). 

The  pioneer  association-type. — The  mechanics  of  salt  marsh 
formation  need  not  be  detailed  here : suffice  it  to  say  that  it  is 
accomplished  through  the  combined  activity  of  plants  and  physio- 
graphic agencies  (see  in  this  connection,  Davis  To).  In  north- 
ern Cape  Breton,  as  in  salt  marshes  along  the  New  England 
coast,  the  pioneer  stage  in  the  salt  marsh  successional  series  is 


37§ 


George  E.  Nichols, 


dominated  by  the  rank-smelling  salt  thatch  ( Spartina  glabra 
alterniflora) . In  typical  cases  this  grass  forms  a fringe  along 
the  outer  edge  of  the  marsh.  It  predominates  from  about  a 
foot  above  mean  low  tide  level  upward  to  within  a few  inches  of 
mean  high  water  mark,  its  actual  vertical  range  being  scarcely 
two  feet.  Except  for  Vaucheria  and  certain  other  filamentous 
algae,  which  commonly  thrive  on  the  muddy  substratum,  the  salt 
thatch  is  ordinarily  the  only  plant  present  in  this  outermost 
zone  ( Spartina  glabra  association-type). 

The  salt  meadozu  association-types. — By  the  time  the  surface 
of  a marsh  has  been  built  up  to  such  a height  that  it  is  submerged 
for  only  a few  hours  daily,  the  pioneer  association-type  has 
given  way  to  salt  meadow : the  rank,  but  open  growth  of  tall, 
coarse  salt-thatch  has  become  superseded  by  a sward  of  lower, 
finer  grasses,  predominantly  the  salt  meadow  grass  ( Spartina 
patens).  Along  with  the  salt  meadow  grass  in  this  association 
( Spartina  patens  association-type)  commonly  grow  in  greater 
or  less  abundance:  Distichlis  spicata,  Triglochin  maritima, 

Plantago  decipiens,  and  Limonium  carolinianum. 

At  this  point  there  is  one  feature  which  is  almost  universally 
associated  with  salt  marsh  building  and  which  demands  a few 
words  of  comment.  During  the  elevation  of  the  substratum 
there  may  arise  in  various  ways,  which  will  not  be  discussed  in 
detail  here  (but  see  in  this  connection,  Yapp  and  Johns  ’17; 
Johnson  and  York  ’15,  pp.  22,  25,  etc.;  Harshberger  T6), 
sloughs  and  depressions  which  become  generally  distributed 
throughout  the  higher  parts  of  the  marsh.  Here  the  depressions 
may  be  deep  or  shallow ; they  may  be  filled  much  of  the  time 
with  more  or  less  stagnant  water  or  may  be  merely  muddy.  In 
the  majority  of  these  so-called  “pans”  the  difference  in  level 
between  their  bottoms  and  the  higher  surfaces  of  the  surround- 
ing meadow  is  but  a matter  of  inches  or  even  fractions  of  an 
inch,  yet  they  present  an  environment  for  plants  which  is  quite 
different  from  that  afforded  by  the  higher,  better  drained  areas. 
The  pans  may  be  quite  barren  of  vegetation  or  they  may  be  well 
populated,  but  their  plant  cover  is  usually  in  marked  contrast 
with  that  of  the  surrounding  meadow.  Especially  characteristic 
of  such  situations  are  Salicornia  europaea  and  Spergularia 
canadensis,  which,  one  or  both,  may  be  the  only  forms  present 
or  which  may  grow  in  association  with  such  species  as  Scirpus 


Vegetation  of  Northern  Cape  Breton. 


379 


nanus,  Glaux  maritima  obtusifolia  and  Puccinellia  maritima. 
Again,  the  pans  may  be  colonized  almost  exclusively  by  the  salt 
thatch,  which  in  such  situations  forms  a dense  but  usually 
depauperate  growth,  while  Distichlis  frequently  skirts  the  edges. 

In  proceeding  from  the  outer  margin  of  a salt  marsh  toward 
the  mainland,  the  general  level  of  the  surface  becomes  slightly 
higher  and  the  general  character  of  the  vegetation  changes 
correspondingly.  But  even  in  the  older,  higher  parts,  owing  to 
the  local  variations  in  elevation  and  drainage,  the  surface  vegeta- 
tion is  far  from  being  uniform.  The  predominant  plant  on  the 
higher,  shoreward  reaches  of  the  salt  meadow  is  Juncus  balticus 
littoralis  ( Juncus  balticus  association-type),  which  in  the  salt 
marshes  of  northern  Cape  Breton  occupies  an  ecological  position 
quite  similar  to  that  held  by  Juncus  Gerardi  in  regions  farther 
south.  The  latter  species  is  seldom  met  with  here.  Associated 
with  the  Juncus,  and  locally  dominant,  may  be  Agrostis  alba 
maritima,  Hierocliloe  odorata,  Scirpus  campestris  paludosus,  and 
Eleocliaris  palustris.  The  two  latter  species  are  especially  well 
developed  in  the  wetter  situations,  where  also  Ranunculus 
Cymbalaria  and  Potentilla  pacifica  are  commonly  present. 
Other  species  characteristic  of  the  shoreward  reaches  of  the 
salt  meadows  are  Triglochin  palustris,  Stellaria  humifusa,  Atri- 
plex  patula  hastata,  Solidago  sempervirens,  and  Aster  novi- 
belgii.  In  addition  to  these,  the  salt  thatch  and  most  of  the 
species  of  the  Spartina  patens  association-type  are  represented 
here:  Spartina  glabra,  Scirpus  nanus,  Spergularia,  and  Sali- 
cornia  in  poorly  drained  depressions ; Spartina  patens  and 
Plantago  decipiens  in  low  but  fairly  well-drained  situations. 
Limoniuni,  however,  apparently  is  confined  to  the  outermost 
meadows. 

C.  THE  ASSOCIATION-COMPLEXES  OF  BRACKISH  MARSHES 

Brackish  marshes  are  of  far  more  general  occurrence  than  salt 
marshes.  To  some  extent  they  are  developed  toward  the  mouths 
of  many  of  the  larger  streams  (Fig.  46),  but  the  finest  examples 
observed  are  situated  at  the  heads  of  Ingonish  Harbor  and  of 
Middle  Harbor  (Aspy  Bay).  The  vegetation  of  brackish 
; marshes  includes  many  of  the  plants  which  have  been  listed  as 
characteristic  of  salt  marshes,  but  it  also  includes  other  species 
which  are  rarely  represented  there.  The  wetter  parts  of  a 


380 


George  E.  Nichols, 


brackish  marsh  ordinarily  support  a rank  growth  of  coarse 
sedges,  notably  Scirpus  occidentalis,  S.  campestris  paludosus, 
Carex  maritima,  and  C.  salina.  These,  singly  or  collectively,  may 
constitute  the  pioneer  association-type.  On  the  higher  parts  of 
the  marsh  the  predominant  forms  usually  are  Juncus  balticus 
littoralis  and  Agrostis  alba  maritima.  Other  forms  which  may 
be  more  or  less  abundantly  represented  in  brackish  marshes  are 
listed  below. 


Figure  46. — Brackish  marsh  near  mouth  of  Barrasois. 


TriAochin  maritima 

o 

T riglochin  palustris 
Hierochloe  odorata 
S p artina  M ichauxia na 
Eleocharis  palustris 
Scirpus  americanus 
Scirpus  rufus 
Eleocharis  palustris 


Carex  Oederi  pumila 
Juncus  pelocarpus 
Atriplex  patxda  hast  at  a 
Spergularia  canadensis 
Potentilla  pacifica 
Plantago  decipiens 
Solidago  sempervirens 
Aster  novi-belgii 


Transitions  from  salt  to  brackish,  from  brackish  to  fresh 
szvamps,  etc. — It  is  impossible  to  draw  a sharp  line  between 


Vegetation  of  Northern  Cape  Breton.  381 

brackish  and  salt  swamps,  on  the  one  hand,  and  between  brackish 
and  fresh  swamps,  on  the  other.  In  the  character  of  the  pre- 
dominant plants,  the  vegetation  of  the  higher,  shoreward 
reaches  of  a well  developed  salt  marsh  almost  invariably 
resembles  that  of  a brackish  meadow,  and  it  commonly  includes 
various  species  characteristic  of  fresh  water  swamps.  Along 
the  shoreward  edge  of  a salt  marsh,  for  example,  in  places  where 
unquestionably  they  are  subject  to  partial  submergence  in  salt 
water,  at  least  by  the  high,  semi-monthly  “spring-tides,”  com- 
monly grow  such  non-halophytic  swamp  species  as  Iris  versi- 
color, Sanguisorba  canadensis,  and  Lysimachia  terrestris; 
Vaccinium  macrocarpon,  Alnus  incana,  Myrica  Gale,  and 
Spiraea  latifolia.  By  way  of  further  illustration,  two  specific 
transitional  series  will  be  briefly  described. 

MacDonald’s  Pond,  near  the  mouth  of  the  Barrasois,  affords 
an  unusually  interesting  illustration  of  this  sort.  At  the  present 
time  the  pond,  which  is  perhaps  half  a mile  long,  is  completely 
shut  in  by  a barrier  beach  and  its  water  is  brackish ; but  within 
twelve  years  it  communicated  with  the  sea  by  a narrow  outlet. 
Around  much  of  the  margin  the  vegetation  is  similar  to  that 
described  in  preceding  paragraphs.  The  area  of  particular 
interest  is  a sheltered  cove,  connected  with  the  main  pond  by  a 
shallow  open  channel  a dozen  feet  wide,  presumably  fed  by 
springs,  and  occasionally  (probably  every  spring)  the  recipient 
of  the  flood  waters  of  the  Barrasois,  which  reach  it  through  a 
channel  ordinarily  dry.  This  cove  has  been  for  the  most  part 
filled  in  to  a depth  of  more  than  a dozen  feet  with  a mixture 
of  peat  and  silt.  From  a small  but  deep  pool  near  the  center 
of  the  swamp  thus  formed  to  the  outlet  of  the  cove  runs  the  open 
channel  already  referred  to.  Toward  the  outlet  of  the  swamp,  the 
vegetation  is  predominantly  that  of  a slightly  brackish  marsh, 
consisting  largely  of  Spartina  Michauxiana,  Agrostis  alba 
maritima,  Scirpus  americanus,  and  Eleocharis  palustris,  together 
with  Potentilla  pacifica,  Triglochin  palustris,  and  Care  x 
maritima.  In  the  open  water  of  the  channel  grow  Ruppia 
maritima  and  Potamogeton  pectinatus.  Bordering  the  pool  is  a 
zone  of  Typha  latifolia,  followed  by  a zone  of  Juncus  balticus 
littoralis.  But  throughout  the  remainder  of  the  area  the  vegeta- 
tion is  predominantly  that  of  a fresh  swamp,  the  more  prominent 
herbs  including  Calamagrostis  canadensis,  Scirpus  cyperinus,  S. 


382 


George  E.  Nichols, 


rubrotinctus,  Carex  canescens  disjuncta,  C.  crinita,  C.  paupercula 
irrigua,  Juncus  filiformis,  Slum  cicutae folium  and  Galium 
palustre.  Considerable  patches  have  been  preempted  by  Myrica 
Gale,  while  Sphagnum  imbricatum  is  locally  abundant.  From  a 
superficial  study  it  would  appear  that  at  the  present  time  the 
fresh  swamp,  presumably  as  a result  of  the  comparatively  recent 
complete  cutting  off  of  MacDonald  Pond  from  the  sea  and  the 
consequently  decreased  salinity  of  the  water,  is  gradually 
encroaching  on  a former  brackish  marsh  whose  vegetation  over 
most  of  the  swamp  is  now  represented  only  by  scattered  relicts. 
But,  as  a matter  of  fact,  the  situation  is  much  more  complicated. 
This  is  merely  suggested  here,  without  attempt  at  explanation, 
by  the  facts  (i)  that  while  there  are  no  living  trees  in  the 
swamp  there  are  numerous  dead  spruces,  and  (2)  that  a sample 
of  the  peat  taken  near  the  margin  of  the  central  pond  showed 
abundant  sphagnum  remains  at  a depth  of  twelve  feet  below  the 
surface. 

Another  interesting  transitional  series,  in  this  case  from  salt 
pond  to  boggy  swamp,  was  observed  along  the  shores  of  North 
Pond,  Aspy  Bay.  Pfere,  starting  from  low  water  mark  and 
proceeding  inland,  within  a distance  horizontally  of  scarcely  a 
hundred  feet  one  passes  through  the  following  associations  : (a) 
Sparitina  glabra  alterniflora  and  Spergularia  canadensis ; (b) 
Spartina  patens;  (c)  Juncus  balticus  littoralis,  Agrostis  alba 
maritima,  and  Ranunculus  Cymbal  aria ; ( d ) Scirpus  occidentalis ; 
(e)  various  species  of  Care x,  Alnus  incana,  Myrica  Gale, 
Vaccinium  macrocarpon,  Chrysophynum  stellatum,  etc.;  (/) 
boggy  swamp  with  Carex  trisperma,  Rynchospora  alba,  Sarra- 
cenia,  Drosera  rotundifolia,  Vaccinium  Oxycoccas,  Chamae- 
daphne,  Ledum,  various  Sphagna,  etc.  Area  a-c  are  below 
mean  high  tide  level,  area  d is  partly  above  and  partly  below, 
area  e is  barely  out  of  reach  of  ordinary  high  tides,  and  area 
f extends  down  to  within  less  than  a foot  (vertically)  of  mean 
high  water  mark. 

In  discussing  the  occurrence  along  the  shore  of  Cold  Spring 
Harbor  of  non-halophytic  vascular  plants,  in  places  where  the 
soil  is  often  covered  by  salt  water,  sometimes  for  as  much  as 
three  or  four  hours  daily,  Johnson  (’15,  p.  no,  etc)  explains 
the  situation  somewhat  as  follows.  The  ground  in  such  places  is 
usually  springy,  and  the  soil  is  saturated  with  fresh  water,  the 


Vegetation  of  Northern  Cape  Breton.  383 

abundance  of  which  “prevents  the  salt  water  from  really  pene- 
trating it.”  In  such  situations,  therefore,  many  upland  and 
fresh  swamp  plants  which  can  stand  more  or  less  inundation 
of  their  shoots  with  salt  water  but  which  cannot  endure  salt 
water  around  their  roots  are  enabled  to  push  down  to  much 
lower  levels  than  usual,  even  growing  below  mean  high  tide 
level.  This  explanation  is  doubtless  the  correct  one,  and  the 
line  of  demarcation  between  halophytic  and  non-halophytic 
associations  is  always  sharper  along  dry  than  along  wet  shores, 
although  even  here  non-halophytic  plants  frequently  invade  areas 
which  are  subject  to  tidal  overflow. 

Of  peculiar  interest  in  this  connection  is  the  occurrence  of 
bryophytes  in  situations  where  they  must  necessarily  be  more 
or  less  exposed  to  the  influence  of  salt  water.  In  northern  Cape 
Breton,  for  example,  Chrysohypnum  stellatum  commonly 
grows  quite  abundantly  on  the  wet  soil  of  brackish  meadows, 
in  company  with  such  vascular  species  as  Triglochin  palustris 
and  Ranunculus  Cymbalaria,  and  the  sphagnums  sometimes 
occur  in  similar  situations.  Sphagnum  palustre  and  Bryum 
inclinatum  have  been  collected  on  exposed  sea  cliffs  well  within 
reach  of  storm  waves,  while  Bryum  fallax  thrives  around 
the  edges  of  salt  ponds.  From  these  and  similar  observations 
elsewhere,  there  seems  little  question  that  while  as  a class  the 
bryophytes  may  be  regarded  as  halophobous,  many  of  them  are 
capable  of  existence  in  habitats  where,  periodically  at  any  rate, 
they  are  bathed  in  brackish  or  salt  water. 

D.  Secondary  Formations  of  the  Hydrarch  Series 

Formation-types  resulting  primarily  from  Human  Activity 

association-complexes  due  to  various  agencies 

In  so  far  as  the  association-types  of  lakes  and  ponds  are  con- 
cerned, the  effect  of  human  activity  has  been  negligible.  The 
vegetation  of  swamps  has  been  variously  modified,  but  it  is  onty 
occasionally  that  it  has  suffered  as  severely  as  that  of  uplands. 
This  state  of  affairs,  in  the  main,  is  easily  explained  by  the  fact 
that  in  this  climate,  with  its  abundant  atmospheric  precipitation, 
the  swamps,  for  the  most  part,  are  of  comparatively  little  value 
from  the  cultural  standpoint.  Instances  of  a more  or  less  pro- 
nounced change  in  swamp  vegetation  from  its  original  character 


384  George  E.  Nichols,  Vegetation  of  Northern  Cape  Breton. 

are  afforded  by  well-drained  swampy  areas  which  have  been 
converted  into  meadow-land.  Here  sedges  and  grasses  pre- 
dominate and  the  vegetation  approximates  more  or  less  closely 
that  elsewhere  described  as  characteristic  of  open,  well-drained 
swamps.  Grazing  cattle  and  sheep  may  bring  about  the  intro- 
duction into  a swampy  area  of  plants  not  previously  present  and 
they  may  appreciably  retard  succession,  but  otherwise  they  do 
not  seriously  modify  the  conditions.  Aside  from  instances  such 
as  those  just  outlined,  any  changes  in  the  vegetation  and  suc- 
cession in  the  swamps  which  are  attributable  to  human  activity 
have  been  largely  due  to  logging  and  fire.  The  former  agency 
may  have  resulted  in  the  removal  of  the  original  forest  cover, 
where  one  was  present,  but  beyond  this  has  had  little  retrogres- 
sive effect  on  the  vegetation  in  the  areas  concerned.  The 
influence  of  fire  is  much  less  in  swamps  than  on  uplands,  since 
the  very  wetness  of  the  substratum  may  prevent  the  complete 
destruction  of  subterranean  plant  organs.  In  general,  the 
association-types  of  secondary  hydrarch  series  appear  to  differ 
little  from  those  of  the  primary  series  as  described  elsewhere. 


THE  NORTHEASTERN  EVERGREEN  CONIFEROUS 
FOREST  CLIMATIC  FORMATION  IN 
NORTHERN  CAPE  BRETON 

I.  GENERAL  CONSIDERATIONS 

Distribution  and  general  character. — By  far  the  greater  part 
of  northern  Cape  Breton,  indeed  nearly  all  the  country  above  an 
elevation  of  approximately  seven  hundred  feet,  is  occupied  by 
this  formation.  With  reference  to  the  general  ecological  aspect 
of  the  vegetation,  however,  the  area  thus  defined  can  be  sub- 
divided into  two  regions:  (i)  the  forest  region  proper,  which 
hereafter  will  be  referred  to  simply  as  the  Forested  Region;  and 
(2)  the  Barrens.  The  extent  of  these  regions  is  roughly  indi- 
cated on  the  map  (Fig.  2).  In  a general  way,  the  forested 
region  can  be  said  to  include  the  upper  mountain  slopes,  together 
with  the  outer  and  lower,  less  exposed  parts  of  the  plateau. 
Here  the  country  is  covered  by  an  almost  unbroken  forest  of 
balsam  fir,  spruce,  and  paper  birch  (Figs.  4,  47,  49).  The  bar- 
rens (Figs.  48,  51,  etc.)  include  primarily  the  higher,  more 
exposed  portions  of  the  plateau,  being  especially  well  developed 
toward  the  interior,  and  occupying  altogether  an  area  estimated 
by  Fernow  (’12,  p.  20)  at  about  375  square  miles.  Here 
forests  of  the  usual  description  are  largely  confined  to  the 
“gulches,”  while  the  country  at  large  is  covered  mainly  by  heath 
and  scrubby  forests,  swamps  and  bogs  (“muskeag”). 

Evergreen  coniferous  forest  in  the  highlands  a climatic,  not 
an  edapliic  climax.— In  a brief  summary  report  of  field  work  in 
Cape  Breton,  Macoun  (’98,  p.  199A),  records  the  following 
observations : “Before  going  to  Cape  Breton,  I had,  like  many 
others,  a very  mistaken  notion  of  the  ‘barrens’12  in  the  northern 
part  of  the  island.  After  spending  some  time  in  the  north  and 
on  the  plateau,  the  conditions  producing  these  barrens  became 
evident.  Along  the  base  of  the  escarpment  bordering  the 
plateau,  the  subsoil  is  generally  impervious,  and  here  spruce  and 
fir  occupy  the  ground.  The  broken  face  of  the  escarpment  is 


12  Macoun  here  seems  to  use  this  term  in  a much  more  comprehensive 
sense  than  that  in  which  it  is  employed  by  the  writer. 


386 


George  E.  Nichols, 


usually  covered  with  broad-leaved  trees,  such  as  maple,  beech 
and  birch,  because  it  is  well  drained.”  In  other  words,  Macoun 
would  seem  to  intimate  that  in  the  mountains,  as  the  writer  has 
shown  to  be  locally  the  case  in  the  lowland,  the  evergreen 
coniferous  forest  is  to  be  regarded  as  an  edaphic  rather  than 


Figure  47.— Primeval  coniferous  forest  of  the  regional  climax  type; 
mountains  near  Cape  North. 

a climatic  climax  association-type.  With  this  opinion  the  writer 
emphatically  disagrees  for  reasons  which  are  briefly  outlined 
below. 

In  ascending  the  mountain  slopes  which  flank  the  plateau, 
there  is  a gradual  transition  from  the  forests  of  the  lowland 
climax  type  to  those  of  the  highland,  a transition  which  has  been 
repeatedly  traced  out  and  verified.  In  passing  upward,  the 


Vegetation  of  Northern  Cape  Breton.  387 

character  trees  of  the  deciduous  climax  formation  disappear  in 
approximately  the  following"  order : beech ; hemlock ; oak  and 
sugar  maple ; white  pine ; red  maple ; yellow  birch.  Except 
for  the  two  species  last  named,  none  of  these  are  represented 
in  the  evergreen  coniferous  climax  forests  of  the  highland.  The 
yellow  birch,  however,  is  frequently  encountered  here  in  edaphi- 
cally  favorable  situations,  while  the  red  maple  is  commonly 
represented  by  shrubby  specimens,  which,  however,  seldom 
attain  the  dignity  of  trees.  It  is  also  significant  that  for  some 
distance  above  the  level  where  it  ceases  to  occupy  a prominent 
position  in  the  forest,  the  sugar  maple  still  maintains  an  impor- 
tant place  in  the  undergrowth,  being  represented  here  by  more 
or  less  abundant,  scraggly,  shrubby  specimens,  which  exhibit 
unmistakable  evidence  of  having  been  repeatedly  killed  back.  It 
is  further  significant  that  there  is  a marked  correlation  between 
the  vertical  distribution  of  most  of  these  trees  in  northern  Cape 
Breton  and  their  north-and-south  geographic  range ; and  it  is 
of  interest  to  observe  that  toward  its  upper  limits  the  deciduous- 
mixed  forest  commonly  is  dominated  by  the  yellow  birch. 

The  facts  just  presented,  and  particularly  the  complete 
absence  on  the  plateau,  even  in  the  many  situations  which  are 
edaphically  favorable,  of  beech,  sugar  maple  and  oak,  hemlock 
and  white  pine,  would  seem  to  indicate  conclusively  that  the 
factors  responsible  for  the  character  of  the  climax  association- 
type  here  are  climatic  and  not  edaphic.  The  controlling  factor 
in  determining  the  upward  extension  of  the  deciduous  forest 
climatic  formation  is  probably  temperature  (see  discussion  else- 
where under  head  of  climate).  But  atmospheric  humidity  may 
also  be  a decisive  factor,  since  the  upper  limit  of  the  deciduous 
climax  forest  coincides  approximately  with  the  lower  limit  of 
the  low-lying  cloud  belt  in  dull  weather,  a feature  which  has  been 
commented  on  earlier  (p.  274). 

The  status  of  the  barrens,  from  the  standpoint  of  ecological 
plant  geography.— The  barrens  are  of  peculiar  interest,  since 
they  present  essentially  the  same  type  of  vegetation  that  prevails 
over  vast  areas  on  the  Labrador  Peninsula  and  throughout  north- 
ern Canada,  regions  concerning  which  almost  nothing  is  known 
ecologically.  So  distinct  in  its  general  aspect  from  that  of  the 
forest  region  proper  is  the  vegetation  of  the  barrens  that  it  was 
at  first  thought  to  constitute  a distinct  climatic  formation. 


388 


George  E.  Nichols, 


Further  investigations,  however,  have  indicated  beyond  question 
that  this  remarkable  formation-complex,  in  northern  Cape 
Breton,  is  the  result  of  edaphic  rather  than  climatic  factors.  The 
climax  association-type  of  uplands  in  the  barrens  bears  much  the 
same  relation  to  the  coniferous  forest  climax  of  the  highlands 
that  the  climax  association-type  of  exposed  headlands  along  the 
seacoast  bears  to  the  deciduous  forest  climax  of  the  lowland. 
The  relation  between  the  edaphic  formation-complex  here  and 


Figure  48. — Barrens  in  mountains  north  of  Barrasois  River  (Scotch- 
man’s Barren)  ; vegetation  closely  approximating  heath ; tamaracks  in 
left  foreground  and  mid-distance. 

that  of  the  highlands  as  a w'hole  is  somewhat  analogous  to  the 
relation  between  the  edaphic  formation-complex  of  the  New 
Jersey  pine  barrens  and  that  of  the  whole  state  of  New  Jersey. 
The  character  of  the  vegetation  in  the  barrens  is  attributable 
very  largely,  directly  or  indirectly,  to  conditions  of  exposure, 
topography,  and  soil.  Along  the  streams  the  climax  forests  of 
the  forested  area  extend  into  the  heart  of  the  barrens,  while, 
conversely,  in  high,  exposed  situations  the  vegetation  of  the 
barrens  reaches  well  toward  the  coast. 

Forest  resources  of  the  region. — In  summing  up  the  results 
of  a timber  survey  of  this  region,  made  a number  of  years  ago. 


Vegetation  of  Northern  Cape  Breton.  389 

Fernow  (T 2,  pp.  20,  24)  estimated  the  commercially  productive 
forest  area  of  the  “1200  square  miles  of  plateau”  at  about  780 
square  miles,  the  unproductive  area  being  largely  occupied  by 
barrens.  He  describes  the  forest  as  “an  almost  unbroken  pure 
balsam  fir  forest,  with  only  15  per  cent,  to  25  per  cent,  of  spruce, 
except  in  the  black  spruce  swamps,  and  about  three  per  cent,  of 
birch,”  in  which  “the  trees  run  from  6 to  14  inches  in  diameter, 
occasionally  up  to  18  inches,  with  36  feet  log  length,  and  ten 
trees  to  the  cord.”  Among  the  sample  plots  measured  in  con- 
nection with  this  survey,  some  180  in  all,  many  ran  from  fifty 
to  sixty  cords  per  acre,  with  an  average  of  at  least  twenty.  The 
forest  is  of  value  chiefly  for  pulpwood ; saw  timber  is  scarce. 
On  a basis  of  the  figures  obtained,  Fernow  estimates  that  the 
area  contains  twelve  million  cords  of  pulpwood,  or  an  amount 
equal  to  that  which  is  computed  to  be  present  in  the  entire 
province  of  Nova  Scotia  outside  of  northern  Cape  Breton,  an 
area  more  than  sixteen  times  as  large.  And  while  these  facts 
are  primarily  of  economic  import,  they  are  also  of  ecological 
interest,  since  they  serve  to  emphasize  the  dissimilarity  between 
the  forests  of  this  region  and  those  in  other  parts  of  Nova 
Scotia. 

Apropos,  it  may  well  be  suggested  here  that  while,  as  has 
been  shown  in  preceding  pages,  conditions  over  much  of  the 
lowland  are  favorable  to  the  development  of  forests  of  the 
deciduous  climax  type,  they  are  even  more  so  to  the  growth  of 
coniferous  forests.  It  is  only  through  their  inability,  in  the 
long  run  and  under  natural  conditions,  to  cope  successfully  with 
their  southern  competitors  that  the  northern  conifers  do  not 
today  constitute  the  predominating  element  in  the  primeval, 
as  well  as  in  the  second  growth  forests  of  this  region.  Both 
climate  and  soil  are  more  favorable  here  than  in  the  highland. 
It  is  the  conviction  of  the  writer  that  the  commercial  production 
of  spruce  and  balsam  fir  in  the  lowland  of  northern  Cape  Breton 
offers  large  possibilities  for  the  future. 

II.  THE  REGIONAL  CLIMAX  ASSOCIATION-TYPE:  THE 
CLIMAX  FOREST 

The  trees  of  the  climax  forest. — The  general  aspect  of  these 
forests  is  well  portrayed  by  Figs.  47,  49.  The  balsam  fir  is  by 
far  the  most  abundant  species,  comprising  ordinarily  more  than 


39° 


George  E.  Nichols, 


75  per  cent,  and  sometimes  fully  85  per  cent,  of  the  stand. 
Individual  trees  may  attain  a trunk  diameter  in  excess  of  six- 
teen inches  with  a height  approaching  seventy  feet,  but  such 
specimens  are  exceptional : the  bulk  of  the  balsams  which  go  to 
make  up  the  mature  forest  run  from  eight  to  twelve  inches  in 


Figure  49. — Primeval  coniferous  forest  of  the  regional  climax  type; 
mainly  balsam  fir;  mountains  north  of  Barrasois  River. 


diameter,  mostly  about  ten,  and  range  around  fifty  feet  in  height. 
The  average  age  of  such  trees,  as  ascertained  in  many  cases 
with  the  aid  of  an  increment  borer,  would  scarcely  exceed  seventy 
years.  Occasional  specimens  are  encountered  which  must  be 
125  or  more  years  of  age,  but  the  exact  age  of  these  larger 
specimens  it  is  seldom  possible  to  determine  accurately,  owing 


Vegetation  of  Northern  Cape  Breton.  391 

to  the  fact  that  almost  invariably  they  are  heart  rotted.  It  is 
a noteworthy  fact,  as  Cooper  (’13,  pp.  17-21)  has  pointed  out, 
that  while  the  balsam  fir  far  outnumbers  all  other  trees  in  the 
forest,  yet,  owing  to  its  susceptibility  to  fungus  attack  and 
consequent  liability  to  windfall,  its  relative  abundance  decreases 
greatly  with  age.  In  other  words,  “its  high  birth-rate  is 
balanced  by  a high  rate  of  mortality.” 

Second  in  importance  to  the  balsam  fir  in  the  climax  forest  is 
the  white  spruce,  which  is  well  distributed  throughout,  com- 
mon, yet  nowhere  approaching  the  balsam  in  abundance,  and 
conspicuous  by  reason  of  its  relatively  large  size.  It  ordinarily 
attains  a diameter  of  sixteen  inches,  sometimes  of  more  than 
two  feet,  and  as  a rule  is  correspondingly  taller  than  the  balsam. 
Black  spruce  is  also  an  important  constituent,  locally  quite 
common,  and  in  size  about  equal  to  the  balsam.  It  never  attains 
here  the  proportions  which  it  exhibits  in  the  Adirondacks  where, 
in  virgin  forests,  trees  three  feet  in  diameter  and  more  than  a 
hundred  feet  high  are  frequent.  These  three  trees  comprise 
the  evergreen  coniferous  element  in  the  climax  forest.  The 
deciduous  element  is  represented  primarily  by  two  species,  the 
paper  birch  and  the  mountain  ash.  The  paper  birch  is  well 
scattered  through  the  forest,  somewhat  less  abundant,  perhaps, 
than  the  white  spruce,  but  prominent  by  reason  of  its  showy 
bark  and  spreading,  broad-leaved  crown.  In  height  it  seldom 
exceeds  the  average  for  the  forest  as  a whole,  and  its  trunk  is 
rarely  as  much  as  a foot  in  diameter.  The  mountain  ash  is  a 
very  characteristic  and  omnipresent  constituent,  usually  a small 
undertree,  but  sometimes  fully  fifty  feet  high  with  a trunk  a foot 
in  diameter.  The  yellow  birch,  though  frequently  represented 
in  favorable  situations,  never  reaches  anywhere  near  the  size 
which  it  attains  in  the  lowland.  Red  maple  is  more  or  less 
scattered  throughout,  but  as  a rule  is  little  more  than  an  under- 
shrub. The  small-toothed  aspen  ( Populus  tremnloides ) also  is 
occasionally  present. 

The  undergrowth  in  the  climax  forest. — Below  is  given  a list 
of  the  characteristic  shrubs  and  herbaceous  vascular  plants  in 
the  coniferous  climax  forest.  Their  general  occurrence  and 
local  abundance  when  present  is  indicated  by  symbols,  as 
explained  elsewhere  (p.  283). 


392 

George  E. 

Nichols, 

Shrubs 

Taxus  canadensis 

cc 

Acer  spicatum 

cc 

Corylus  ro strata 

cf 

Acer  pennsylvanicum 

cf 

Ribes  prostratum 

cf 

Lonicera  canadensis 

cf 

Amelanchier  sp. 

CO 

Viburnum  cassinoides 

cf 

Nemopanthus  mucronata 

cf 

Viburnum  pauciflorum 

fo 

Herbaceous  Vascular  Plants 


Phcgopteris  Dryopteris 

fl 

Oxalis  Acetosella 

cc 

Phegopteris  polypodioides 

cf 

Aralia  nudicaulis 

cc 

Pteris  aquilina 

cf 

Cornus  canadensis 

cc 

Aspidium  spinulosum  var. 

fo 

Moneses  uniflora 

cf 

Osmunda  cinnamomea 

cf 

Pyrola  secunda 

CO 

Osmunda  Claytoniana 

ff 

Monotropa  uni  flora 

CO 

Clintonia  borealis 

cc 

Monotropa  Hypopitys 

CO 

Maianthemum  canadcnse 

cc 

Epigaea  repcns 

cf 

Streptopus  roseus 

CO 

Chiogenes  hispidula 

CC 

Habenaria  obtusata 

cf 

Trientalis  americana 

cc 

Epipactis  sp. 

CO 

Linnaea  borealis  americana 

cc 

List  era  cor  data 

fo 

Solidago  macrophylla 

ff 

Coptis  trifolia 

cc 

Aster  acuminatus 

cl 

Mitella  nuda 

cl 

Except  for  occasional  colonies  of  the  yew,  the  shrubs  and 
herbaceous  vascular  plants  in  the  undergrowth  seldom  form 
dense  masses  of  vegetation.  The  ground  is  usually  occupied  by 
a continuous  but  rather  open  growth  of  the  various  species  men- 
tioned above.  As  on  Isle  Royale,  the  most  conspicuous  element 
in  the  herbaceous  ground-cover  is  the  bryophyte  contingent, 
whose  profuse  development  here  in  these  coniferous  forests  is 
in  striking  contrast  to  its  paucity  in  the  deciduous  climax  forests 
of  the  lowland.  Almost  everywhere  the  ground  is  overlain  by  a 
soft,  verdant  carpet  of  Bazzania  trilobata,  Hypnum  Schreberi, 
and  Hylocomium  splendens,  with  which  are  associated  Dicranum 
undulatum,  Rhytidiadelphus  lorcus,  R.  triquetrus,  Pt ilium  crista- 
castrensis  and  species  of  Sphagnum.  In  the  drier  places  the 
hypnum  alone  may  predominate,  in  moist  situations  the  sphag- 
nums.  Ordinarily  all  the  species  mentioned,  except  perhaps  the 
sphagnums,  are  well  represented.  The  ecological  significance  of 


Vegetation  of  Northern  Cape  Breton. 


393 


this  bryophyte  ground  cover  in  hindering  evaporation  and  imped- 
ing drainage,  thereby  influencing  not  only  the  moisture  of  the 
substratum,  but  also  its  temperature,  aeration,  and  toxicity,  can 
hardly  be  questioned.  Usually  the  surface  layer  of  living  plants 
is  underlain  by  a more  or  less  spongy  mass  of  incompletely 
decomposed  vegetable  remains  (the  duff),  which  commonly  is  six 
inches  or  more  in  thickness.  Corticolous  liverworts  and  mosses 
in  general  are  much  more  poorly  developed  in  coniferous  than  in 
deciduous  climax  forests,  although  the  lichens  occupy  a promi- 
nent position,  particularly  the  beard  lichen  ( Usnea  barbata), 
which  in  well-lighted  situations  commonly  drapes  itself  in  grace- 
ful festoons  from  the  branches  of  the  trees. 

Reproduction  of  the  climax  trees. — In  his  ecological  investiga- 
tion of  the  northeastern  evergreen-coniferous  climax  forest,  as 
developed  on  Isle  Royale,  Cooper  (’13,  pp.  42,  43)  arrived  at 
the  following  conclusions,  which  were  based  in  large  part  on  the 
intensive  study  of  carefully  selected  quadrats.  For  successful 
reproduction  the  balsam  fir  requires  abundant  light,  given 
which  it  will  germinate  and  thrive  in  any  sort  of  situation.  In 
the  forest,  reproduction  is  practically  confined  to  the  openings 
caused  by  windfall.  “The  forest  is  a complex  of  windfall  areas 
of  differing  ages,  the  youngest  made  up  of  dense  clumps  of  small 
trees,  and  the  oldest  containing  a few  mature  trees  with  little 
young  growth  beneath.  The  history  of  a windfall  area  is  as  fol- 
lows. After  the  debris  has  disintegrated  sufficiently  to  allow 
abundant  light  to  reach  the  ground,  a new  generation  of  trees 
springs  up,  approximately  even-aged,  composed  of  the  three 
dominant  species  [balsam  fir,  white  spruce,  and  paper  birch], 
Abies  always  greatly  preponderant.  During  the  continued 
development  of  this  group  most  of  the  individuals  are  at  various 
times  eliminated,  . . . Because  of  the  dense  shade  no  new 
individuals  can  start  beneath  them  and  the  final  outcome  is  a 
group  composed  of  a few  large  trees,  approximately  even-aged, 
in  which  Abies  has  nearly  or  quite  lost  its  position  of  dominance 
to  Betnla.”  The  resultant  forest  is  thus  “a  mosaic  or  patchwork 
which  is  in  a state  of  continual  change.”  Yet  “the  forest  as  a 
whole  remains  the  same,  the  changes  in  various  parts  balancing 
each  other.” 

Turning  now  to  northern  Cape  Breton,  it  would  seem  that  the 
ecological  relations  of  the  balsam  fir  here  are  somewhat  different 


Trans.  Conn.  Acad.,  Vol.  XXII 


1918 


23 


394 


George  E.  Nichols, 


from  those  just  described  for  Isle  Royale.  Here,  as  there,  open- 
ings due  to  windfall  are  a characteristic  feature  of  the  forest; 
and  the  immediate  sequel  to  windfall  is  a commonly  prolific  crop 
of  balsam.  Some  of  the  young  trees  may  originate  from  seeds 
shed  previously  to  the  windfall,  but  which  have  been  lain  dormant 
on  the  ground  for  want  of  conditions  suitable  to  germination. 
Others  doubtless  arise  from  seeds  shed  only  a short  time  before 
the  windfall,  or  else  contemporaneously  with  or  subsequent  to  it. 
But  many  of  the  young  trees  represent  specimens  which  were 
already  present  in  the  forest  previous  to  the  windfall.  For  while 
the  reproduction  of  the  balsam  is  most  prolific  in  the  windfall 
areas,  it  is  by  no  means  confined  to  them.  It  is  seldom  that  the 
shade  on  the  forest  floor  is  sufficiently  dense  to  prevent  repro- 
duction, and  almost  everywhere  the  undergrowth  in  a forest  of 
the  climax  type  includes  numerous  small,  scattered  balsams, 
mostly  suppressed  but  ready  to  take  advantage  of  any  chance 
opening  which  may  occur  in  the  canopy  overhead.  Such  open- 
ings, to  be  sure,  are  commonly  due  to  windfall,  since  except  in 
protected  situations  the  balsam  seldom  dies  a natural  death.  It 
is  a not  infrequent  occurrence  for  groups  of  trees  to  be  over- 
thrown by  the  wind,  thus  giving  rise  to  openings  of  considerable 
extent,  but  more  commonly  it  is  only  scattered  individuals  which 
are  blown  down  at  one  time.  The  influence  of  the  openings  thus 
created  is  probably  twofold:  (i)  more  light  is  introduced  into 
the  lower  layers  of  vegetation,  and  ( 2 ) wherever  sunlight  reaches 
the  forest  floor  the  moss  carpet,  together  with  the  more  or  less 
spongy  underlying  layers  of  duff  and  humus,  tend  to  become 
somewhat  dried  out  and  in  consequence  warmer  and  better 
aerated.  This  latter  indirect  influence,  the  possible  significance 
of  which  is  suggested  by  Cooper  (’13,  p.  20),  it  seems  to  the 
writer,  is  of  fully  as  great  importance  here  in  northern  Cape 
Breton,  at  least  so  far  as  the  balsam  is  concerned,  as  is  the  direct 
influence  of  increased  illumination.  The  understory  of  balsams 
in  a deciduous  forest  is  much  more  thrifty  than  that  in  a conif- 
erous forest,  a circumstance  which  might  be  explained  by  the 
more  favorable  soil  conditions  there : so  far  as  shade  is  con- 
cerned, this  is  generally  greater  in  a deciduous  than  in  a 
coniferous  forest,  at  least  during  the  growing  season.  But  with- 
out question  increased  illumination  is  a very  important  direct 
factor,  and  perhaps  the  most  important  one,  affecting  the  growth 


Vegetation  of  Northern  Cape  Breton. 


395 


of  the  balsam.  In  this  connection  attention  may  be  called  to 
earlier  remarks  (p.  285)  regarding  the  ecological  relations  of 
the  balsam. 

The  white  spruce  and  paper  birch  are  much  more  dependent  on 
an  adequate  light  supply  for  successful  reproduction  than  is  the 
balsam  fir.  This  is  demonstrated  by  the  relative  abundance  of 
the  young  growth  of  these  two  species  in  a windfall  area  or  clear- 
ing, as  contrasted  with  the  great  scarcity  of  any  but  large  trees 
in  the  forest.  In  the  case  of  the  paper  birch,  to  quote  Cooper 
(’13,  p.  22),  “low  birth-rate  is  compensated  by  a very  low 
mortality  and  it  is  thus  able  to  maintain  itself  in  making  a good 
proportion  of  the  mature  stand.”  The  same  observation  may 
apply  equally  well  to  the  white  spruce,  which  apparently  is 
relatively  more  abundant  here  than  on  Isle  Royale.  The  black 
spruce  grows  best  in  well  lighted  situations,  but,  like  the  balsam, 
it  is  capable  of  maintaining  itself  for  years  in  moderate  shade. 

With  reference  to  their  tolerance  of  shade  in  this  climate,  the 
writer  would  arrange  the  climax  trees  of  the  northeastern 
coniferous  forest  climatic  formation  in  northern  Cape  Breton  in 
about  the  following  order:  paper  birch  and  aspen  (very 

intolerant),  white  spruce  (intolerant),  balsam  fir,  black  spruce, 
and  mountain  ash  (tolerant),  and  yellow  birch  (very  tolerant). 


III.  THE  EDAPHIC  FORMATION-COMPLEX  OF  THE  REGION 
A.  Preliminary  Observations 

One  of  the  most  perplexing  features  of  this  region,  when  it 
comes  to  the  exact  analysis  and  delimitation  of  the  various 
formation-types,  is  the  manner  in  which  these  overlap  and  inter- 
grade. This  condition  is  attributable  primarily  to  the  abundance 
of  atmospheric  moisture.  In  less  humid  climates  soil  moisture 
plays  an  all  important  role  in  determining  the  character  and  dis- 
tribution of  vegetation,  and  as  a result  differences  in  soil  and 
topography  are  associated  with  corresponding  differences  in  plant 
cover.  In  general  it  can  be  stated  that  the  influence  of  soil  and 
topography  on  the  character  and  distribution  of  plant  associations 
is  least  pronounced  in  humid  climates ; most  pronounced  in  arid 
climates : or,  in  other  words,  that  this  influence  is  inversely  pro- 
portional to  the  dryness  of  the  climate.  This,  tendency  toward 
uniformity  in  a humid  region  is  of  course  due  in  part  to  the  fact 


396 


George  E.  Nichols , 


that  here  many  soils,  which  in  a less  humid  region  would  be  too 
dry  to  permit  the  development  of  the  types  of  association  which 
characterize  the  better  soils,  are  kept  constantly  moist.  It  may 
also  be  due  to  the  fact  that  bare  rock  outcrops,  which  in  them- 
selves are  unable  to  retain  water  except  in  crevices,  become 
rapidly  overgrown,  except  where  they  are  too  steep,  by  a layer 
of  lichens  and  bryophytes  which  create  a water-retaining  sub- 
stratum and  thus  tend  to  produce  ground  conditions  similar  to 
those  found  in  soils  which  naturally  would  be  more  favorable  to 
plant  growth.  In  the  coniferous  forest  region  of  northern  Cape 
Breton,  and  probably  in  other  similar  regions  as  well,  this 
tendency  toward  uniformity  is  accentuated  by  the  fact  that  in  the 
upland  forests,  owing  largely  to  the  prolific  development  of 
mosses  and  liverworts  and  the  copious  accumulation  of  humus, 
not  only  is  the  substratum  kept  constantly  moist,  but  it  is  invaria- 
bly acid  to  litmus,  thus  approximating  the  conditions  which 
prevail  in  bogs  and  in  the  majority  of  the  swamps.  In  less 
humid  climates,  many  of  the  species  which  here  are  characteristic 
of  uplands,  or  which  grow  both  on  uplands  and  in  bogs  and 
swamps,  are  restricted  to  situations  of  the  latter  sort.  The 
tendency  for  different  edaphic  formation-types  to  merge  into  one 
another  is  exhibited  to  some  degree  in  the  lowland  region  of 
northern  Cape  Breton ; it  is  quite  pronounced  in  the  forested 
portion  of  the  highlands ; but  it  reaches  its  culmination  in  the 
barrens,  where  it  is  almost  impossible  to  draw  a sharp  line 
between  the  vegetation  of  uplands  and  that  of  the  swamps. 

B.  Formations  of  the  Xerarch  Series 

i.  The  Formation-types  of  Ordinary  Uplands  in  the  Forested 

Region 

a.  THE  ASSOCIATION-COMPLEXES  OF  WELL-DRAINED  UPLANDS 

In  comparing  xerarch  successions  on  ordinary,  well-drained 
uplands  here  with  those  of  the  lowland,  the  most  striking  differ- 
ence is  seen  in  the  character  of  the  climax  association-type. 
There,  a balsam  fir-spruce-paper  birch  forest  may  represent 
merely  a passing  stage  in  the  succession:  in  all  edaphically 
favorable  situations  it  is  a temporary  association-type,  destined 
in  the  course  of  time  to  be  superseded  by  a forest  of  the 
deciduous  type.  Here,  however,  a forest  of  this  sort  represents 


Vegetation  of  Northern  Cape  Breton. 


397 


the  culminating  stage  in  the  succession : it  is  a permanent 

association-type.  Throughout  most  of  the  forested  region  in  the 
highland  this  coniferous  forest  climax  has  been  attained,  and 
it  is  only  in  edaphically  unfavorable  situations  or  in  places 
where  the  original  forest  has  been  destroyed  by  fire  that  the 
more  primitive  stages  in  the  succession  are  encountered.  The 
association-types  of  exposed  hilltops  may  resemble  those  of 
similar  situations  in  the  barrens,  but,  on  the  whole,  the  sequence 


Figure  50. — Low  coniferous  woodland  on  plateau  west  of  Ingonish. 


and  general  character  of  the  preliminary  successional  stages  in 
the  highland  is  essentially  similar  to  what  has  been  described 
for  the  lowland  and  therefore  need  not  be  discussed  further.  As 
a rule  the  succession  takes  place  rapidly,  the  trees  of  the  climax 
forest  being  present  from  the  outset,  and  the  various  stages  are 
more  or  less  telescoped. 

b.  THE  ASSOCIATION-COMPLEXES  OF  POORLY  DRAINED  UPLANDS 

Forests  of  the  regional  climax  type  attain  their  optimum 
development  on  well-drained  slopes.  But  over  a considerable 
portion  of  the  forested  region  the  country  is  flat  or  rolling,  with 
a tendency  to  be  poorly  drained,  and  the  prevailing  type  of  vege- 
tation here  is  low,  more  or  less  swampy  woodland  (Fig.  50).  No 


398 


George  E.  Nichols, 


sharp  line  can  be  drawn  between  woodlands  of  this  description, 
which  constitute  an  edaphic  climax  association-type,  and  forests 
of  the  regional  climax  type.  Essentially  the  same  species  may 
be  present  in  both  cases.  Here,  however,  the  trees  average 
scarcely  twenty-five  feet  in  height,  and  black  spruce  may  be  quite 
as  abundant  as  balsam,  while  swamp  species,  notably  Osmunda 
cinnamomea  and  the  sphagnums,  commonly  predominate  in  the 
undergrowth.  Associations  of  this  sort  may  originate  through  a 


Figure  51. — Summit  of  low  hill  in  barrens;  mountains  west  of  Ingonish; 
vegetation  in  immediate  foreground,  dwarf  shrub  heath ; in  mid-distance 
(vicinity  of  figure  and  beyond),  mainly  dwarf  shrub-spruce  heath.  The 
low,  bushy  spruce  in  center  foreground  was  about  150  years  old. 

hydrarch  successional  series,  but  more  commonly  the  pioneer 
stages  are  xerophytic,  the  swampy  condition  being  induced  very 
largely  through  the  activity  of  vegetation  in  retarding  drainage. 
Parts  of  the  plateau  occupied  by  barrens  are  commonly  skirted  on 
all  sides  by  low  woodland,  which  forms  a transition  zone  between 
these  areas  and  those  congenial  to  forests  of  a more  mesophytic 
character.  Raised  bogs  have  been  developed  locally  on  uplands 
in  the  forested  region,  but  these  are  especially  characteristic 
of  the  barrens  and  will  be  discussed  under  that  head. 


Vegetation  of  Northern  Cape  Breton. 


399 


2.  The  Formation-types  of  Ordinary  Uplands  in  the  Barrens 

a.  THE  ASSOCIATION-COMPLEXES  OF  WELL-DRAINED  UPLANDS 

The  rock  face-crevice  complex. — Over  most  of  the  plateau  the 
bed  rock  is  covered  by  a thin  soil  which  may  be  residual  or 
extraneous  in  its  origin.  Here  and  there,  however,  rounded 
knolls  or  blocks  of  granite  and  syenite  rise  conspicuously,  and 
on  these  may  be  found  rock-face  and  crevice  associations  essen- 
tially similar  to  those  which  have  been  described  as  characteristic 
of  rock  outcrops  in  the  lowland. 

But  the  prevailing  pioneer  type  of  vegetation  on  uplands  in  the 
barrens  is  some  sort  of  a heath.  In  the  heath  the  lichens,  notably 
the  cladonias,  are  invariably  conspicuous,  while  sedges  and 
grasses,  shrubs  and  scrubby  trees  occupy  a position  of  varying 
importance. 

The  dwarf  slir.ub  heath  association-type. — This  is  characteris- 
tically developed  on  exposed  hill  tops,  where  the  soil  may  sup- 
port only  the  scantiest  kind  of  a plant  cover  (foreground  of  Fig. 
51).  In  such  situations  the  ground  in  places  is  bare;  elsewhere 
it  is  overlain  by  a sparse  mat  of  cladonias  and  Racomitrium 
lanuginosum,  or  maintains  a stubby  growth  of  Polytrichum 
juniperinum,  P.  piliferum,  and  Ceratodon  purpureus.  Of  the 
seed  plants  peculiar  to  such  habitats,  Potentilla  tridentata  is 
worthy  of  note,  but  particularly  characteristic  are  the  four 
shrubs : Empetrum  nigrum,  which  forms  low,  sprawling  mats ; 
Vaccinium  uliginosum,  which  occurs  in  depressed  circular 
patches;  Vaccinium  Vitis-Idaea,  which  scrambles  over  the 
ground  and  frequently  is  intricately  interwoven  in  the  lichen  mat ; 
and  Vaccinium  pennsylvanicum  an gusti folium,  a form  of  blue- 
berry only  a few  inches  high.  In  addition  to  these,  there  is 
usually  a scattering  of  other  plants,  particularly  ericaceous 
shrubs,  all  of  which  are  noticeably  impoverished. 

Typical  dwarf  shrub  heath  occurs  locally  throughout  the  bar- 
rens, but  in  a pure  state  is  nowhere  extensively  developed.  In 
exposed  situations  it  may  constitute  a permanent  association- 
type,  i.  e.,  an  edaphic  climax.  But  more  commonly  it  seems  to 
represent  a temporary  stage,  destined  to  be  superseded  by  dwarf 
shrub-spruce  heath,  into  which  it  nearly  everywhere  merges. 
In  places  dwarf  shrub  heath  very  evidently  is  a retrogressive  type 
which  has  arisen  subsequent  to  the  destruction  of  dwarf  shrub- 


400 


George  E.  Nichols, 


spruce  heath ; but  more  commonly  it  represents  a primitive 
phase.  Characteristic  plants  here,  in  addition  to  those  already 
specifically  mentioned,  are  the  following: 

Lichens 

Cladonia  rangifernia 
Cladonia  sylvatica 
Cetraria  islandica 
Sphaeophorus  coralloides  Pers. 

Seed  Plants 

Juniperus  communis  Montana  Kalmia  angustifolia 
Ledum  groenlandicum  Kalmia  polifolia 

Rhododendron  canadense  M elampyrum  lineare 

The  sedge— grass  heath  association-type. — This  occurs  in 
somewhat  moister,  less  exposed  situations  than  the  dwarf  shrub 
heath,  as  for  example,  or  rather  dry  slopes.  The  ground  is 
usually  covered  by  a luxuriant  growth  of  cladonias,  which  may 
be  replaced  locally  by  Racomitrium  lanuginosum  or  occasionally 
by  xerophytic  species  of  Sphagnum,  such  as  S',  capillaceum 
tenellum  and  S',  tenerum.  The  pre-dominant  vascular  plants  are 
the  sedge,  Scirpus  caespitosus,  and  the  grass,  Calamagrostis 
Pickeringii.  Other  herbaceous  plants  generally  present  are  as 
follows : 

Lycopodium  sitchense  Cornus  canadensis 

Lycopodium  annotinum  pungens  Prenanthcs  trifoliolata 
Deschampsia  flexuosa  Solidago  uliginosa 

M elampyrum  lineare  Aster  nemoralis 

In  addition  to  these,  the  woody  species  characteristic  of  the 
dwarf  shrub-spruce  heath  are  well  represented,  but  for  the 
most  part  by  small  specimens,  scattered  and  relatively  inconspicu- 
ous. Like  the  preceding  association-type,  the  sedge-grass  heath 
is  nowhere  extensively  developed,  and  it  displays  a constant 
tendency  to  pass  over  into  dwarf  shrub-spruce  heath. 

The  dwarf  shrub-spruce  heath  association-type. — This  is  one 
of  the  most  widely  distributed  and  most  distinctive  types  of  vege- 
tation in  the  barrens.  It  commonly  occupies  the  upper  slopes 


Cladonia  alpestris 
Cladonia  coccifera 
Cladonia  crispata 
Cladonia  pyxidata 


Vegetation  of  Northern  Cape  Breton.  401 

of  hills  (Figs.  51,  52),  and  in  general  prevails  on  well-drained 
uplands  wherever  the  conditions  of  exposure  are  such  as  to  pre- 
vent the  development  of  a more  mesophytic  type  of  vegetation. 
At  first  sight  an  area  occupied  by  this  association-type  appears 
as  a crowded,  labyrinthine  series  of  low  mounds  or  hummocks, 
irregular  in  size  and  shape,  but  averaging  perhaps  from  three  to 
ten  feet  in  diameter  by  from  one  to  two  feet  in  height.  The 
hummocks  are  densely  overgrown  with  cladonias  and  support  a 
thick  growth  of  low  shrubs,  mostly  ericads.  Depressed,  bushy 
trees,  mainly  black  spruce,  scarcely  two  feet  high  but  spreading 


Figure  52. — Dwarf  shrub-spruce  heath  ; barrens  in  mountains  west  of 
Ingonish. 


out  laterally  over  a radius  of  several  feet,  constitute  an  important 
element  in  the  vegetation,  growing  on  or  alongside  the  hum- 
mocks. Here  and  there,  scattered  tamaracks  may  be  conspicu- 
ous by  reason  of  the  fact  that  they  project  somewhat  above  the 
general  surface  level  of  the  surrounding  vegetation,  which 
otherwise  maintains  a nearly  uniform  height  at  from  two  to  two 
and  a half  feet  above  the  floor  of  the  depressions  which  separate 
the  hummocks.  In  typical  dwarf  shrub-spruce  heath,  the 
depressions  between  the  hummocks  are  open  and,  aside  from  the 
cladonia  mat  which  nearly  everywhere  covers  the  ground,  their 
vegetation  is  scanty. 

The  following  list  includes  the  more  characteristic  plants  of 
dwarf  shrub-spruce  heath : 


402 


George  E.  Nichols, 
Lichens 


Cladonia  alpestris  Cladonia  rangiferina 

Cladonia  sylvatica  Cetraria  islandica 


Bryophytes 

Sphagnum  capillaceum  tenellum  Leucobryum  glaucum 
Sphagnum  tenerum  Rac omitrium  lanuginosum 

Ptilidium  ciliare  Hypnum  Schreberi 


Vascular  Plants 


Pteris  aquilina 
Abies  balsamea 
Picea  mariana 
Larix  laricina 

Juniperus  communis  montana 
Maianthemum  canadense 
Myrica  Gale 
Pyrus  melanocarpa 
Amelanchier  sp. 

Empetrum  nigrum 
Nemopanthus  mucronata 


Cornus  canadensis 
Andromeda  glaucophylla 
Chamaedaphne  calyculata 
Epigaea  repens 
Kalmia  angustifolia 
Kalmia  polifolia 
Ledum  groenlandicum 
Rhododendron  canadense 
Vaccinium  canadense 
Vaccinium  pennsylvanicum 
Viburnum  cassinoides 


Any  of  the  other  species  mentioned  earlier  as  characteristic  of 
sedge-grass  heath  may  grow  here  also,  but  these,  for  the  most 
part,  are  confined  to  the  depressions  between  the  hummocks. 

The  structure  of  the  hummocks  (Fig.  53)  is  extremely  inter- 
esting. Examination  shows  them  to  be  due  entirely  to  plant 
activity.  Internally  they  consist  of  an  intricate  mass  of  incom- 
pletely decomposed  vegetable  debris : the  sort  of  structure  com- 
monly referred  to  as  “raw  humus.”  Ordinarily  the  bulk  of  the 
material  has  been  derived  from  the  lichens  and  from  the  leaves 
of  the  various  shrubs  which  inhabit  the  surface  of  the  hummock, 
the  whole  being  bound  together  by  the  stems  and  roots  of  the 
surface  vegetation.  In  some  cases  the  sphagnum  has  contrib- 
uted very  largely  to  the  formation  of  the  hummocks : in  one 
instance  the  excavation  of  a hummock  two  feet  high,  whose  sur- 
face vegetation,  aside  from  various  shrubs,  consisted  entirely  of 
Sphagnum  capillaceum  tenellum,  showed  the  whole  hummock  to 
have  been  built  up  by  this  moss,  whose  remains,  still  in  a fine 


Vegetation  of  Northern  Cape  Breton.  403 

state  of  preservation,  extended  nearly  to  the  bottom,  where,  at 
the  very  base  of  the  hummock  and  overlying  the  gravelly  sub- 
stratum, was  a thin  layer  of  Leucobryum  remains.  It  is  evident 
that  for  the  most  part  the  formation  of  these  hummocks  is  a 
result  of  the  combined  activity  of  the  lichens,  particularly  the 
cladonias,  and  the  ericaceous  shrubs.  They  have  arisen  some- 
what as  follows.  Previous  to  their  formation  the  ground  was 
covered  by  a thin  mat  of  mosses  and  lichens  in  which  grew  vari- 


Figure  53. — Detail  view  of  hummock  in  dwarf  shrub  heath  association- 
type;  Cladonia  alpestris,  Chamaedaphne , Ledum,  etc.;  barrens  in  moun- 
tains west  of  Ingonish. 

ous  herbaceous  plants  and  shrubs : essentially  the  same  condition 
which  prevails  in  sedge-grass  heath  and  which  still  persists  in 
the  open  depressions  between  the  hummocks.  Where  edaphic 
conditions  are  favorable  the  cladonias  exhibit  a marked  tendency 
to  grow  upward,  but  they  are  unable  to  do  so  to  any  extent  with- 
out some  sort  of  support.  The  needed  support  is  furnished  by 
the  shrubs  which,  where  they  grow  close  enough  together, 
afford  a sort  of  scaffolding  upon  or  around  which  the  lichens  are 
able  to  push  upward.  As  the  shrubs  gradually  become  buried 


4°4 


George  E.  Nichols, 


below  they  grow  above,  at  the  same  time  branching  more  or  less- 
profusely.  And  as  the  branches  become  covered  over  they  pro- 
duce copious  adventitious  roots,  with  the  result  that  the  original 
number  of  physiologically  independent  individuals,  as  viewed  at 
the  surface  of  the  hummock,  becomes  multiplied  many  times. 
The  shrubs,  therefore,  which  cover  the  surface  of  a hummock 
have  been  derived  directly,  in  large  part  at  least,  from  pre- 
existing shrubs : they  antedate  the  hummock  itself.13 

The  genetic  relationship  between  dwarf  shrub  and  sedge- 
grass  heath,  on  the  one  hand,  and  dwarf  shrub-spruce  heath, 
on  the  other,  has  already  been  suggested.  During  the  evolution 
of  the  present  association-type,  various  of  the  herbaceous  vascular 
plants  characteristic  of  the  more  primitive  stages  either  disappear 
or  else  become  in  large  part  or  wholly  confined  to  the  depres- 
sions : to  situations  where  there  is  no  great  depth  of  humus  and 
where  the  soil  relations  presumably  are  more  favorable  than  on 
the  hummocks.  This  is  true,  for  example,  of  both  Scirpus  and 
Calamagrostis,  and  of  such  forms  as  Lycopodium,  Potentilla, 
Solidago,  and  Aster.  At  the  same  time,  scrubby  trees  become 
increasingly  conspicuous. 

In  its  ecological  aspect,  an  association  of  the  sort  just  depicted 
certainly  approximates  very  closely  dwarf  shrub  heath,  as  defined 
by  Warming  (’09,  pp.  210-214).  It  agrees  in  the  nature  of  the 
underlying  soil,  in  the  dominance  of  lichens  and  ericaceous 
shrubs,  in  the  low  stature  of  the  vegetation,  and  in  the  copious 
production  of  raw  humus : this  latter  a phenomenon  which, 
according  to  Warming,  “must  be  regarded  as  the  most  charac- 
teristic peculiarity  of  heath.”  It  would  seem  to  differ  from  typical 
heath  primarily  in  the  presence  of  various  arborescent  species 
which,  in  more  favorable  situations,  attain  much  larger  dimen- 
sions than  here.  But  while  any  of  the  trees  of  the  climax 
coniferous  forest  (with  the  exception  of  yellow  birch  and  red 
maple)  may  be  represented  here,  it  is  significant  that  black  spruce 
is  invariably  predominant ; that  tamarack,  which  is  practically 
absent  from  the  climax  forest,  is  usually  a prominent  constituent; 
and  that,  on  the  other  hand,  balsam  fir,  the  predominant  tree 
in  forests  of  the  regional  climax  type,  is  of  very  subordinate 


13  In  this  connection,  see  observations  by  Ganong,  quoted  on  p.  447. 


Vegetation  of  Northern  Cape  Breton.  405 

importance.  In  its  typical  development,  then,  the  writer  would 
regard  this  type  of  association  as  a true  heath.14 

Transition  from  heath  to  Krummholz. — All  intergradations 
are  found  between  typical  dwarf  shrub-spruce  heath  and 
Krummliolz , the  association-type  to  be  treated  next,  and  in  this 
connection  the  behavior  and  ecological  relations  of  the  spruce 
and  other  evergreen  conifers  has  an  important  bearing.  As  the 
principal  species  concerned,  the  black  spruce  will  serve  to  illus- 
trate the  points  in  question.  Like  the  ericaceous  shrubs,  this 
species  appears  at  an  early  stage  in  the  development  of  the  heath : 
it  is  antecedent  with  reference  to  the  hummocks.  Through  the 
death  of  the  primary  leader,  the  extensive  development  and 
copious  branching  of  the  lateral  shoots,  and  commonly  also 
through  vegetative  reproduction  by  layering,  it  characteristically 
assumes  a low,  compact,  rounded,  shrub-like  habit.  So  closely 
may  one  of  these  bushy  spruces  conform  with  the  contour  of  the 
hummock  alongside  which  it  grows  that  on  superficial  examina- 
tion it  appears  to  be  growing  on  the  hummock  itself ; but 
ordinarily  the  relationship  is  very  different.  For  the  shade  pro- 
duced by  these  clumps  of  spruce  has  an  important  local  effect 
on  the  nature  of  the  vegetation,  in  that  it  inhibits  the  growth 
of  lichens  and  thereby  prevents  or  checks  hummock  formation. 
In  some  areas  the  depressions  between  adjacent  hummocks  are 
completely  filled  in  by  a dense  snarl  of  scrubby  spruces  which 
rise  to  about  the  same  general  level  as  the  low  vegetation  which 
tops  the  hummocks.  From  a distance  the  surface  contour  of 


11  Warming  (’09,  p.  210)  defines  heath  as  “A  treeless  tract  that  is 
mainly  occupied  by  evergreen,  slow-growing,  small-leaved  dwarf-shrubs 
and  creeping  shrubs  which  are  largely  Ericaceae.”  But  the  use  of  the 
term  is  not  wholly  restricted  to  such  areas.  Warming  himself  recognizes 
lichen-heath  and  moss-heath  (op.  c.,  pp.  205,  208),  and  Graebner  (’01, 
pp.  26,  27),  while  distinguishing  as  most  representative  areas  of  the  sort 
specified  by  Warming,  extends  the  term  to  include  “not  only  areas  domi- 
nated by  ericaceous  shrubs,  but  open  tracts  in  which  there  is  neither  a 
good  tree  growth  nor  a close  grass  turf;  [in  which]  ligneous  plants 
dominate,  especially  low  shrubs.  [Thus,]  what  we  call  pine  or  oak  bar- 
rens would  probably  be  included  in  Graebner’s  heath”  (quotation  from 
Cowles’  review  of  Graebner’s  book).  Applying  the  term  in  this  latter 
sense,  Harshberger  (Ti,  pp.  165-168)  regards  the  “plains”  of  the  New 
Jersey  pine-barrens  as  heath.  Rubel  (’14,  p.  237)  would  restrict  the 
use  of  the  term  heath  to  “ericoid-leaved  bushland.” 


4°6  George  E.  Nichols, 

such  an  area  appears  quite  flat  and  easy  to  travel,  but  one  soon 
learns  to  steer  clear  of  these  “tanglefoot”  barrens,  as  an  old 
trapper  who  served  as  guide  for  the  writer  aptly  termed  them, 
whenever  possible.  Barrens  of  this  sort  obviously  represent  a 
transition  stage  between  the  dwarf  shrub-spruce  heath  asso- 
ciation-type and  the  Krummholz  association-type.  Not  only 
is  the  arborescent  element  in  the  vegetation  present  in  increased 
abundance,  but  the  character  of  the  undergrowth  is  different. 


Figure  54. — Krummholz  in  immediate  foreground,  passing  into  low 
woodland  or  forest  scrub  behind  the  figure;  barrens  in  mountains  west 
of  Ingonish. 

For  the  presence  of  the  spruce  not  only  causes  the  exclusion  of 
certain  species,  but  favors  the  introduction  of  others.  Under- 
neath these  dwarf  evergreen  trees,  wherever  they  occur,  may  be 
found  any  or  all  of  the  liverworts  and  mosses  characteristic  of 
the  climax  forest  of  the  region  (e.  g.,  Bassania,  Dicranum 
undulatum,  Hylocomium  splendens,  Ptilium ),  together  with 
various  of  the  herbaceous  plants  (e.  g.,  Clint  onia,  Coptis, 
Linnaea). 

The  Krummholz  association-type. — This  differs  from  heath  in 
the  following  important  respects:  (1)  Dwarf,  bushy  trees 


Vegetation  of  Northern  Cape  Breton.  407 

( Krummholz ) predominate  and  form  a relatively  closed  stand. 
( 2 ) The  lichens  which  characterize  the  heath  (together  with  the 
hummocks  which  they  form)  are  either  absent  or  else  poorly 
developed,  while  ericaceous  shrubs  occur  here  mainly  as  an 
understory  and  are  of  subordinate  importance  to  arborescent 
species,  (j)  The  undergrowth  approximates  that  of  the  climax 
coniferous  forests  of  the  region,  essentially  the  same  list  of 
bryophytes,  herbaceous  vascular  plants,  and  shrubs  being 
characteristic  of  each.  (4)  The  ecological  aspect  is  much  more 


Figure  55. — Low  Krummholz  association-type  with  scattered  tamaracks, 
many  of  them  dead,  projecting  up  above  general  level  of  surrounding 
vegetation;  barrens  in  mountains  west  of  Ingonish. 


mesophytic.  In  typical  Krummholz  (Figs.  54,  55)  the  trees 
range  around  three  and  four  feet  in  height  and  commonly  pro- 
duce a dense  tangle  through  which  it  is  exceedingly  difficult  to 
force  one’s  way.  It  is  a type  of  association  characteristic  of 
situations  in  the  open  barrens  which  are  somewhat  sheltered  from 
wind.  In  the  opinion  of  Dr.  Harvey,  who  accompanied  the 
writer  in  1916,  the  Krummholz  of  the  barrens  in  northern  Cape 
Breton  is  a close  ecological  counterpart  of  the  Krummholz  on 
Mount  Ktaadn,  concerning  which  he  has  written  (’03,  p.  34)  : 
“It  seems  then  that  the  Krummholz  forest  is  almost  as  mesophytic 
as  the  Picea-Abies  combination  ....  which  very  evidently  is 


408 


George  E.  Nichols, 


the  climatic  mesophytic  forest  of  this  district.”  Krummholz 
differs  from  forest  scrub  not  only  in  the  lesser  height  of  the 
trees,  and  in  their  more  pronounced  tendency  to  approximate  the 
Krummholz  growth  form,  but  in  the  lesser  abundance  of  the 
balsam  fir. 

Factors  responsible  for  failure  of  forests  to  develop. — True 
alpine  conditions  are  found  nowhere  in  northern  Cape  Breton. 
This  is  evidenced  by  the  complete  absence  of  an  arctic-alpine 
flora.  On  Mount  Franey,  the  highest  measured  mountain  in 
Nova  Scotia,  for  example,  no  species  were  observed  which  are 
not  equally  abundant  at  lower  elevations,  while  with  the  excep- 
tion of  perhaps  a few  forms  such  as  Betula  pumila,  Vaccinium 
uliginosum,  and  V . pennsylvanicum  angustifolium,  the  flora  of 
the  interior  plateau  scarcely  differs  in  its  composition  from  that 
of  the  upper  mountain  slopes.  The  general  failure  of  forests  to 
develop  in  the  barrens  can  be  ascribed  very  largely  if  not  wholly 
to  edaphic  factors,  especially  to  the  combined  influence  of  snow 
and  wind  during  the  winter  months.  Heavy  winds  prevail  on 
the  barrens  intermittently  at  all  seasons,  but  particularly  in 
winter.  The.  primary  effect  of  the  wind  at  this  season  is  to 
sweep  the  snow  from  the  more  exposed  sites  and  pile  it  up  in 
the  more  sheltered  situations.  Exposed  hill  crests  may  be  swept 
entirely  bare,  while  in  some  of  the  ravines  great  drifts  fully  fifty 
feet  in  depth  may  accumulate.  In  general,  it  is  apparent  that  the 
height  of  the  trees,  with  the  possible  exception  of  the  tamarack, 
is  closely  correlated  with  the  depth  of  the  snow  in  winter.  In 
exposed  situations  any  branches  which  project  above  the  surface 
of  the  snow  are  liable  to  be  killed  by  excessive  transpiration  or 
through  the  sand-blast-like  action  of  the  wind-driven  snow. 
Individual  shoots  may  survive  a few  mild  winters,  but  then 
comes  a severe  winter  and  they  too  are  killed.  In  the  case  of 
forest  scrub,  an  association-type  to  be  described  presently,  it  is 
evident  that,  in  spite  of  the  apparently  exposed  position  of  the 
low  hills  on  which  it  is  commonly  developed,  local  conditions 
favor  the  accumulation  of  snow  drifts  in  much  the  same  manner 
that  sand  dunes  are  built  up  along  the  seacoast. 

Age  of  dwarf  trees. — In  this  connection,  a few  observations 
regarding  the  ages  of  some  of  the  dwarf  trees  may  be  of  interest. 
The  tamarack  shown  in  Fig.  56,  situated  near  the  crest  of  the  hill 
pictured  in  Fig.  51,  was  found  to  have  more  than  150  annual 


Vegetation  of  Northern  Cape  Breton.  409 

rings;  and  about  the  same  number  was  counted  in  a cross 
section  of  the  trunk  of  a balsam  fir,  scarcely  three  feet  high, 
but  with  a trunk  seven  inches  in  diameter.  Knee-high  spruces 
more  than  fifty  years  old  are  common  in  exposed  situations,  one 
of  those  in  the  foreground  of  Fig.  51,  scarcely  a foot  in  height, 
having  more  than  a hundred  annual  rings. 

The  forest  scrub  association-type  — From  a distance,  many  of 
the  low  hills  in  the  barrens  appear  to  be  well  wooded,  but  closer 


Figure  56. — Gnarled  tamaracks,  aged  about  150  years,  at  summit  of  low 
hill  shown  in  Fig.  51 ; barrens  in  mountains  west  of  Ingonish. 


inspection  commonly  reveals  a most  remarkable  type  of  associa- 
tion. Because  of  the  size  of  the  trees,  many  of  which  may  be 
as  much  as  twenty  feet  high,  it  should  be  classed  as  forest;  yet 
it  is  an  abortive  attempt  at  forest  development  rather  than  true 
forest.  Three  trees  predominate : the  balsam  fir,  the  black 
spruce,  and  the  tamarack,  and  one  and  all  are  battered  and 
weather-beaten,  betraying  unmistakably  the  severity  of  the 
atmospheric  forces  to  which  they  have  been  subjected.  In  this 
connection  the  dissimilar  behavior  of  the  three  constituent  trees 
under  these  adverse  conditions  is  of  much  interest. 


4io 


George  E.  Nichols, 


The  balsam  fir  commonly  possesses  a short,  stocky  trunk  from 
three  to  six  feet  high,  according  to  the  depth  of  the  snow  blanket. 
This  trunk  ranges  in  diameter  up  to  more  than  a foot  (in  one 
case  sixteen  inches),  and  some  of  the  trees  must  be  well  over 
two  hundred  years  old  (one  six  inch  trunk  showed  more  than  150 
annual  rings),  an  unusual  age  for  the  balsam  in  northern  Cape 
Breton.  The  total  height  of  the  tree  may  be  little  greater  than 
that  of  its  stubby  trunk:  the  lateral  branches,  usually  borne  in 


Figure  57. — Habit  sketch  of  balsam  fir  growing  in  forest  scrub  associa- 
tion-type; barrens  in  mountains  west  of  Ingonish.  This  particular  tree 
is  ten  feet  high  (overall)  and  has  a spread  of  more  than  a dozen  feet 
with  a trunk  diameter  of  nearly  a foot. 


profusion  near  its  summit,  spread  out  widely,  giving  rise  to  a 
dense,  flat-topped  crown,  low  but  commonly  ten  or  a dozen  feet 
broad  and  drooping  nearly  to  the  ground.  But  as  a rule,  upon 
the  death  of  the  primary  leader,  a new  leader  is  developed  which 
tends  to  continue  the  upward  growth  of  the  trunk.  After  a few 
years,  the  length  of  the  interval  depending  on  the  severity  of 
the  winters,  this  leader  may  be  killed  and  replaced  by  a third, 
and  so  on.  More  than  twenty  dead  leaders  have  frequently  been 
counted  on  a single  tree.  Often  several  leaders  may  be  active  at 
the  same  time,  but  usually  one  of  them  soon  gains  a marked 


Vegetation  of  Northern  Cape  Breton.  41 1 

ascendancy  over  the  others.  Very  often  a leader  which  rises  six 
or  eight  feet  above  the  main  body  of  the  tree  will  have  had  all 
its  foliage  blasted  away  by  the  wind-driven  snow  except  for  a 
small,  pyramidal  crown  at  the  very  tip.15  The  general  aspect  of 
these  trees  is  suggested  by  the  accompanying  sketch  (Fig.  57). 

Usually  quite  different  in  its  behavior  from  the  balsam  fir  is 
the  black  spruce.  In  the  balsam,  while  the  lateral  branches  may 
be  capable  of  assuming  the  functions  of  the  leader,  it  would 
appear  that  they  are  able  to  do  so  only  when  very  young,  and 
more  often  than  not  the  leader  seems  to  originate  adventitiously 
from  either  the  main  axis  of  the  tree  or  a lateral  branch.  In 
the  spruce,  on  the  other  hand,  the  potential  capacity  for  radial 
growth  in  the  normally  dorsiventral  lateral  branches  is  much 
more  pronounced,  and  this  capacity  is  less  restricted  to  the 
younger  branches.  Upon  the  death  of  the  primary  leader,  a 
number,  often  nearly  all,  of  the  lateral  branches  tend  to  assume 
the  radial  habit,  thus  producing  a clump  of  leaders,  all  of 
approximately  equivalent  rank.  As  a result,  while  one  leader 
may  sometimes  become  more  prominent  than  the  rest,  the  spruce 
commonly  acquires  a bushy  habit  quite  different  from  that  of  the 
balsam.  This  dissimilarity  of  habit  in  the  two  trees  is  often 
strikingly  exhibited  in  the  Krnmmholz  association-type : the 

balsam  here  is  constantly  tending  to  send  a vigorous  leader  up 
above  the  general  level  of  the  surrounding  vegetation  and 
invariably  possesses  a short,  sturdy  trunk  (Fig.  58)  ; while  the 
spruce  adapts  itself  readily  to  the  prostrate  Krummholz  habit 
and  is  virtually  devoid  of  a distinct  trunk. 

The  tamarack  behaves  differently  from  either  the  balsam  or 
the  spruce,  being  apparently  better  able  than  these  species  to 
withstand  the  rigorous  winter  climate.  The  trees  exhibit  a 
gnarled,  scraggly  aspect,  but  seldom  are  killed  back  to  any 
extent. 

Sometimes  a forest  of  the  sort  under  consideration  is  well  nigh 
impenetrable,  and  the  undergrowth  is  essentially  that  of  the 
coniferous  climax  forest  of  the  region.  But  more  often  the  trees 
occur  singly  or  in  groups,  with  open  spaces  between  in  which 
the  vegetation  is  made  up  largely  of  the  species  characteristic  of 


13  A different  explanation  for  a similar  phenomenon  in  the  spruce  has 
been  offered  by  Ganong  (’04,  pp.  188,  189). 


412 


George  E.  Nichols, 


heath.  In  general,  this  association-type  is  intermediate  in 
character  between  heath  and  typical  forest. 

The  ecological  status  of  the  tamarack  in  northern  Cape  Breton. 
— The  status  of  the  tamarack  in  the  lowland  has  already  been 
referred  to.  In  the  barrens  it  is  a common  tree,  but  throughout 
the  forested  region  of  the  highlands  it  is  absent  or  very  rare  in 


Figure  58. — Weather-beaten  balsam  fir;  barrens  in  mountains  west  of 
Ingonish.  This  tree  measured  eight  feet  high  (overall)  and  had  a trunk 
less  than  three  feet  high  (in  position  indicated  by  arrow)  but  seven  inches 
in  diameter  and  with  more  than  150  annual  rings.  The  present  leader,  to 
left  of  trunk,  shows  well  the  effect  of  heavy  westerly  winds  (from  right 
in  picture)  and  wind-driven  snow. 

upland  forests,  being  confined  mainly  to  open  swamps.  The 
evident  scarcity  of  this  tree  in  all  but  open  situations  is  correlated 
with  the  fact  that  it  is  primarily  a pioneer  species : it  is 

notoriously  intolerant  of  shade.  As  a result,  except  in  barrens, 
swamps,  or  other  open  situations,  it  has  almost  everywhere  been 
crowded  out  in  competition  with  the  more  tolerant  climax  trees. 

The  low  woodland  association-type. — This  is  essentially  similar 
to  the  low  woodland  type  of  poorly  drained  uplands  described 


Vegetation  of  Northern  Cape  Breton.  413 

for  the  forested  region.  It  may  occupy  like  situations  in  the 
barrens,  but  here  it  also  is  a frequent  type  on  moist,  fairly  well 
drained  hillsides  which  are  protected  from  the  wind. 

Summary  of  successional  relations. — It  will  be  seen  that  in  a 
general  way  the  association-types  of  well-drained  uplands  in  the 
barrens  have  been  arranged  in  an  ascending  series ; that  there 
are  all  gradations  between  dwarf  shrub  heath  and  sedge-grass 
heath  at  the  one  extreme  and  typical  forest  at  the  other.  Incident 
to  the  special  discussion  of  the  association-types,  various  succes- 
sional relationships  have  been  pointed  out.  But  while  it  is  con- 
ceivable that  in  the  course  of  time  the  associations  of  relatively 
primitive  types  are  everywhere  destined  to  become  superseded  by 
associations  of  more  advanced  types,  as  a matter  of  fact  this  is 
not  generally  the  case.  For  the  degree  of  mesophytism  capable 
of  attainment  in  the  majority  of  sites  is  limited  by  edaphic 
factors,  and  any  of  the  association-types  described  above  may 
constitute  locally  an  edaphic  climax. 

b.  THE  ASSOCIATION-COMPLEXES  OF  POORLY  DRAINED  UPLANDS 

Although  a distinction  may  be  made  between  well-drained  and 
poorly  drained  uplands  in  the  barrens,  as  a matter  of  fact,  as  has 
been  intimated  earlier,  it  is  practically  impossible  to  draw  sharp 
lines  of  demarcation.  Owing  to  the  character  of  the  vegetation, 
especially  to  the  influence  of  the  almost  universally  developed 
lichen-bryophyte  ground  cover  in  retarding  drainage,  an  area 
which  originally  may  have  been  well-drained  rapidly  becomes  less 
so,  and  there  are  few  areas  in  which  water  cannot  be  squeezed 
out  of  a peaty  substratum  at  almost  any  time  of  the  year. 

In  protected  situations,  wet,  poorly  drained  uplands  may  sup- 
port low,  swampy  forests  of  (mainly)  black  spruce,  with  an 
undergrowth  of  Alnus  incana,  Osmunda  cinnamomea,  and  the 
like : forests  which  might  almost  equally  well  be  treated  under 
the  head  of  hydrarch  successions.  Further,  the  occurrence  of 
sphagnum  hummocks  in  areas  occupied  by  heath  has  already 
been  mentioned.  On  flat  upland  areas  from  which  the  water 
runs  off  slowly  or  where  it  tends  to  collect  locally  in  shallow 
rock  basins,  as  well  as  in  various  other  situations  where  drainage 
conditions  are  such  as  to  favor,  at  least  locally,  the  development 
of  the  sphagnums,  bogs  and  boggy  swamps  may  arise  on  uplands. 


4'4 


George  E.  Nichols, 


The  discussion  of  these  is  deferred  until  later  (see  under  head 
of  raised  bogs,  p.  433). 

3.  The  Formation-types  of  Uplands  along  Streams 

THE  ASSOCIATION-COMPLEXES  OF  RAVINES  AND  VALLEYS 

The  association-types  of  ravines. — Streams  in  the  forested 
region  for  the  most  part  flow  through  ravines  or  broadly 
V-shaped  valleys.  The  character  of  the  stream-bank  and  cliff 


Figure  59. — Low  forest  in  ravine,  with  barren  hill-top  above ; barrens 
in  mountains  west  of  Ingonish. 


vegetation  here  is  essentially  similar  to  that  already  described  for 
lowland  streams.  Ravine  forests  exemplify  further  the  general 
tendency  of  the  vegetation  of  uplands  in  this  region  toward  uni- 
formity, since  they  differ  scarcely,  if  at  all,  from  the  forests  of 
ordinary  uplands. 

Ravine  vegetation  in  the  barrens  (Fig.  59),  in  general, 
resembles  that  of  the  forested  region,  and  the  forest-clad  slopes 
here  may  afford  a striking  contrast  to  the  barren  aspect  which 
prevails  on  adjoining  exposed  uplands.  In  shallow  ravines  the 
woodland  is  low,  but  in  the  deeper  “gulches”  the  trees  attain 
considerable  size. 


Vegetation  of  Northern  Cape  Breton. 


4i5 


The  association-types  of  open  valleys.-. — While  practically  all 
the  larger  streams  on  their  way  to  the  sea  run  for  long  distances 
through  deep  gorges  and  ravines,  on  the  plateau  itself  most  of 
the  streams  flow  through  broad,  shallow,  characteristically  flat- 
floored  valleys,  but  little  below  the  general  level  of  the  surround- 
ing country.  The  slopes  which  flank  these  valleys  may  be  covered 
with  low  woodland,  or  in  the  barrens  by  Krummholz.  Their 
floors  are  commonly  occupied  by  “hay  marshes,”  alder  thickets, 
and  swampy  woodland,  which  will  be  discussed  under  hydrarch 
successions. 

C.  Formations  of  the  Hydrarch  Series 

1.  The  Formation-types  of  Lakes  and  Ponds 

a.  introductory 

Small  lakes  and  ponds  of  all  sizes,  but  mostly  quite  shallow, 
are  freely  interspersed  among  the  countless  low  hills  which  go 
to  make  up  the  surface  of  the  plateau  and  occur  scattered  here 
and  there  along  the  seaward  slopes  of  the  highland.  Many  of 
them  lie  at  the  sources  or  along  the  courses  of  the  innumerable 
streams  which  originate  in  the  barrens,  but  a large  proportion 
are  devoid  of  any  definite  outlet.  Ponds  of  the  latter  type  are 
especially  common  on  the  plateau  where,  owing  to  the  abundant 
precipitation  and  the  impermeable  nature  of  the  rock  floor,  more 
or  less  permanent  bodies  of  water  tend  to  collect  in  basins  of 
any  description.  On  an  undulating,  rock-floored  table-land  such 
as  this,  the  number  of  depressions  suitable  to  pond  formation  is 
naturally  very  great,  but  the  number  of  ponds  actually  present 
is  even  greater.  This  is  due  to  the  fact  that,  in  addition  to  those 
whose  presence  is  conditioned  by  the  character  of  the  topography, 
there  are  numerous  ponds  which  bear  no  relation  whatever  to 
the  topography,  whose  presence  is  attributable  primarily  to  the 
activity  of  vegetation.  The  manner  in  which  ponds  of  this  latter 
sort  arise  will  be  discussed  in  some  detail  in  later  paragraphs 
(p.  449  et  seq.).  On  the  highland,  as  in  the  lowland  (while  there 
are  plenty  of  apparent  exceptions,  particularly  in  the  case  of  well- 
drained  water  bodies)  there  is  a general  tendency  for  lakes  and 
ponds  to  become  clogged  up  through  vegetative  activity,  and  in 
this  way  many  basins  formerly  occupied  by  ponds  have  become 
more  or  less  completely  filled  in. 


416 


George  E.  Nichols, 


b.  THE  ASSOCIATION-COMPLEXES  OF  WELL-DRAINED  LAKES  AND 

PONDS 

The  plants  named  in  the  subjoined  list  are  characteristic  of 
well-drained  lakes  and  ponds  in  the  highland,  growing  either  in 
the  deeper  water  or  in  the  shallows  along  the  shore.  Extended 
comment  seems  hardly  worth  while,  since  in  their  local  distribu- 
tion and  ecological  relations  they  conform  closely  with  what  has 
been  described  for  similar  areas  in  the  lowland. 


Figure  6o. — Shallow  pond  in  mountains  north  of  Barrasois  River; 
aquatic  vegetation  and  narrow  marginal  fringe  of  swamp  shrubs. 


Sphagnum  cuspidatum  Torreyi 
Drepanocladus  Sendtneri 
Drepanocladus  scorpioides 
Fontinalis  sp. 

Isoetes  sp. 

Equisetum  fluviatile 
Sparganium  angustifolium 
Potamogeton  natans 
Potamogeton  Oakesianus 


Carex  aquatilis 
Carex  filiformis 
Carex  rostrata 
Eriocaulon  septangulare 
Nymphaea  variegate 
Castalia  odorata 
Ranunculus  Flammula  reptans 
Nymphoides  Idcunosum 
Lobelia  Dortmanna 


Vegetation  of  Northern  Cape  Breton. 


4i7 


Dulichium  arundinaceum  Utricularia  vulgaris 

Eleocharis  palustris  vigens  Utricularia  intermedia 

Scirpus  subterminalis 


The  character  of  the  marginal  vegetation  might  perhaps  more 
appropriately  be  considered  in  connection  with  swamps,  but  two 
phases  will  be  briefly  mentioned  at  this  point.  Between  the 
water’s  edge  and  the  adjoining  upland  vegetation  there  may 
occur  only  a narrow  fringe  of  swamp  thicket  (Fig.  60),  made  up 
of  such  shrubs  as  the  following: 


Myrica  Gale 
Alnus  incana 
Spiraea  latifolia 
Rosa  nitida 
Ilex  verticillata 


Nemopanthus  mucronata 
Chamaedaphne  calyculata 
Kalmia  angustifolia 
Rhododendron  canadense 
V iburnum  cassinoides 


Elsewhere,  however,  intervening  between  this  thicket  and 
ordinary  summer  low  water  mark  there  may  be  a strip  of  sandy 
or  rocky  beach,  of  varying  width,  which  supports  an  open  swamp 
association  of  an  essentially  pioneer  type.  Characteristic  plants 
of  such  a habitat  are  the  following : 


Scapania  nemorosa 
Sphagnum  sp. 

Lycopodium  inundatum 
Agrostis  hyemalis 
Carex  filiformis 
Carex  Michauxiana 
Carex  Oederi  pumila 
Carex  stellulata 
Juncus  brevicaudatus 
Ranunculus  Flammula  reptans 
Drosera  longifolia 


Drosera  rotundifolia 
Hypericum  canadense 
Hypericum  virginicum 
Viola  cucullata 
Viola  pollens 
Bartonia  iodandra 
Vaccinium  macrocarpon 
Lycopus  uniflorus 
Utricularia  cor  nut  a 
Aster  nemoralis 
Aster  radula 


Very  commonly,  at  least  locally,  the  lake  is  bordered  by 
swamps  of  a more  advanced  type,  but  these  are  better  considered 
under  the  head  of  swamps. 


C.  THE  ASSOCIATION-COMPLEXES  OF  UNDRAINED  PONDS 

In  the  number  and  abundance  of  seed  plants,  the  aquatic  vegeta- 
tion of  undrained  ponds  as  a rule  is  inferior  to  that  of  well- 


418 


George  E.  Nichols, 


drained  ponds.  Of  species  with  submerged  or  floating  leaves 
the  most  commonly  represented  are  N ymphaea  variegata  and 
Castalia  odorata,  Eriocaulon  septangulare,  Ranunculus  Flammula 
reptans  and  U tricularia  intermedia.  In  addition  to  these,  various 
sedges  may  grow  in  the  shallow  water  around  the  margin  or 
elsewhere,  such  species  as  Eleocharis  palustris  vigens,  Carex 
oligosperma  and  Scheuchzeria  palustris,  together  with  the  buck- 
bean,  Menyanthes  trifoliolata.  Of  particular  importance,  how- 
ever, because  of  their  frequently  prolific  growth,  are  the  aquatic 
sphagnums,  notably  Sphagnum  Pylaisei  and  5'.  cuspidatum 
(including  the  var.  Torreyi),  and  certain  filamentous  algae.  But 
there  is  the  greatest  variation  in  the  vegetation  even  of  closely 
adjacent  and  seemingly  quite  similar  ponds.  One  may  be  quite 
choked  up  with  aquatic  sphagnums,  while  in  the  next  there 
is  scarcely  any  vegetation  save  a dense  growth  of  algae  on  the 
bottom.  One  may  contain  a rank  growth  of  Eleocharis,  its 
neighbor  a similar  growth  of  Menyanthes,  or  neither  of  these 
species  may  be  present ; and  so  on.  Practically  all  undrained 
ponds  are  mucky  at  the  bottom  and  along  the  shores.  The 
dynamics  of  the  vegetation  in  lakes  and  ponds  are  discussed  in 
later  paragraphs. 


2.  The  Formation-types  of  Lake-,  Spring-,  and  Precipitation- 

swamps 

a.  THE  ASSOCIATION-COMPLEXES  OF  WELL-DRAINED  SWAMPS 

As  elsewhere  suggested,  throughout  the  region  of  coniferous 
forests,  wherever  the  ground  is  sufficiently  wet,  there  is  a 
tendency  for  the  substratum,  through  the  influence  of  vegetation 
in  obstructing  the  drainage,  to  become  boggy.  In  view  of  this 
fact,  it  would  not  have  been  at  all  surprising  to  find  that  swamps 
similar  to  the  undrained  type  of  the  lowlands  were  entirely  lack- 
ing here.  But  this  is  not  the  case.  While  the  majority  of  the 
swamps  belong  to  the  undrained  or  poorly  drained  types,  swamps 
are  frequently  encountered  which  unmistakably  are  of  the 
well-drained  type.  The  following  list  of  plants,  from  an  open 
swamp  situated  on  a fairly  steep,  springy  hillside  in  the  forested 
region,  scarcely  a mile  from  the  edge  of  the  barrens,  is  quite 
characteristic  of  well-drained  swamps  in  this  region : it  has  been 
practically  duplicated  in  other  similar  areas. 


Vegetation  of  Northern  Cape  Breton.  419 


Taxns  canadensis 

Thalictrum  dioicum 

Calamagrostis  canadensis 

Drosera  rotundifolia 

Cinna  latifolia 

Spiraea  latifolia 

Glyceria  canadensis 

Amelanchier  sp. 

Scirpus  caespitosus 

Sanguisorba  canadensis 

Scirpus  hudsonianus 

Rosa  nitida 

Eriophornm  virginicum 

Viola  blanda 

Rynchospora  alba 

Viola  cucullata 

Carex  crinita 

Chamaedaphne  calyculata 

Car  ex  flava 

Lonicera  caendea 

Carex  stellulata 

Viburnum  cassinoides 

J uncus  brevicaudatus 

Eupatorium  purpureum 

Smilacina  trifolia 

Solidago  rugosa 

Iris  versicolor 

Aster  acuminatus 

Habenaria  clavellata 

Aster  nemoralis 

Habenaria  dilatata 

Aster  puniceus 

Spiranthes  Romanzoffiana 

Aster  radula 

Myrica  Gale 

Aster  umbellatus 

Alnus  incana 

Cirsium  muticum 

Aside  from  relatively  steep,  springy  slopes,  swamps  of  the 
well-drained  type  are  commonly  developed  along  streams,  in 
places  where  the  ground  is  subject  to  occasional  inundation  (see 
further  under  head:  formation-types  along  streams,  p.  456). 

The  vegetation  in  swamps  of  the  well-drained  type  is  apt  to 
include  more  or  less  admixture  of  bog  species,  as  shown  by 
the  above  list,  but  these  occupy  a subordinate  position  and 
sometimes  even  the  omnipresent  ericad,  Chamaedaphne,  is 
absent.  The  only  occurrence  of  Typha  lati folia  noted  on  the 
plateau  was  in  a swamp  of  this  description.  Well-drained 
swamps  are  far  less  frequent  in  the  barrens  than  in  the  forested 
region,  but  even  here  they  are  by  no  means  absent,  particularly 
along  the  larger  streams. 

b.  THE  ASSOCIATION-COMPLEXES  OF  POORLY  DRAINED  SWAMPS 

Under  this  head,  here  as  in  the  lowland,  may  be  included  a 
large  number  of  swampy  areas  which,  in  the  character  and 
ecological  relations  of  their  vegetation,  appear  to  be  intermediate 
between  the  well-drained  and  the  undrained  types.  There  is  one 
group  of  swamps  in  particular  which  seems  to  fit  in  under  this 


420 


George  E.  Nichols, 


bead  better  than  under  any  other,  swamps  which  are  quite  com- 
monly encountered  along  the  shores  of  well-drained  lakes. 
Locally  along  the  margins  of  these  lakes  (Fig.  6i)  there  have 
been  formed  broad,  nearly  level  beaches,  sometimes  twenty-five 
or  fifty  feet  in  width,  which  lie  somewhat  above  the  level  of 
the  lake  in  summer,  but  are  submerged  during  winter  and  early 
spring,  at  times  when  the  outlet  is  blocked  up  by  the  ice. 

At  an  early  period  in  its  development  the  vegetation  in  such 
an  area  is  essentially  as  described  for  the  beach  in  connection 


Figure  6i. — Small,  well-drained  lake  with  border  of  marshy  swamp ; 
mountains  north  of  Barrasois  River. 

with  the  vegetation  of  well-drained  lakes  and  ponds  (p.  417)  : 
an  open  swamp  association  of  a pioneer  type.  In  the  course  of 
time,  under  favorable  conditions,  the  more  or  less  discontinuous 
plant  cover  characteristic  of  this  early  stage  may  become  con- 
tinuous. Largely  through  the  activity  of  the  sedges,  Cares 
fliformis,  Cares  oligosperma,  and  Rynchospora  alba,  a shallow 
layer  of  peat  is  formed  and  the  level  of  the  swamp’s  surface 
is  gradually  raised  higher.  It  is  worthy  of  special  note  that  the 
sphagnums  play  a relatively  insignificant  part  in  the  building  up 
process : the  cushion-forming  species  so  conspicuous  in  bog 


Vegetation  of  Northern  Cape  Breton. 


42 1 


formation  are  usually  absent  or  poorly  developed.  About  the 
only  form  at  all  abundant  is  Pylaisei,  a rather  delicate  species 
which,  with  the  liverwort,  Cephalozia  fhiitans,  commonly  covers 
the  peaty  substratum  in  among  the  sedges  with  a thin,  felty  mat. 
At  an  early  stage  in  its  development,  in  addition  to  the  sedges 
already  mentioned,  the  vegetation  of  such  an  association-type 
includes,  among  others,  the  following  species : 


Schizaea  pusilla 
Lycopodium  inundatum 
Scheuchzeria  palustris 
Scirpus  caespitosus 
Rynchospora  alba 


Rynchospora  fusca 
Bartonia  iodandra 
Drosera  longi folia 
Vaccinium  macrocarpon 
Utricularia  cornuta 


As  time  goes  on,  Scirpus  caespitosus,  at  first  scattered,  comes 
to  occupy  the  ground  more  and  more  completely,  forming  a 
rather  dense  sward  and  crowding  out  most  of  the  species  listed 
above,  except  such  as  are  able  to  persist  in  local  depressions. 
The  Scirpus  is  responsible  for  a still  further  elevation  of  the  sub- 
stratum, but  the  peat  in  such  a swamp  is  almost  invariably 
shallow,  seldom  exceeding  two  feet  in  thickness.  Commonly 
associated  with  the  Scirpus  in  this  association-type  are  the  fol- 
lowing : 


Calamagrostis  canadensis 
Carex  Michauxiana 
Carex  pauciflora 
Habenaria  blephariglottis 


Epilobium  palustre 
Drosera  rotundifolia 
Sarracenia  purpurea 
Aster  nemoralis 


The  vegetation  is  predominantly  herbaceous,  with  Scirpus  as 
the  character  plant.  As  a rule,  however,  there  is  a scattering  of 
low  shrubs,  such  forms  as  Myrica,  Spiraea,  Andromeda, 
Chamaedaphne,  Kalmia  polifol-ia , Rhododendron,  and  Lonicera 
caerulea,  which,  along  the  shoreward  margin,  commonly  form 
a thicket.  An  association  of  this  sort  bears  a marked  resemblance 
to  bog-meadow,  as  described  later  in  connection  with  raised 
bogs.  In  many  situations  it  seems  without  question  to  represent 
an  edaphic  climax.  Failure  for  succession  to  proceed  further  is 
probably  correlated  with  an  inability  on  the  part  of  the  cushion- 
forming sphagnums  to  gain  control,  an  inability  for  which  the 
periodic  inundation  seems  in  some  way  to  be  responsible. 


422 


George  E.  Nichols, 


C.  THE  ASSOCIATION-COMPLEXES  OF  UNDRAINED  SWAMPS 

Ecological  characteristics  of  the  more  important  hog  species  of 
Sphagnum. — Emphasis  has  been  laid  earlier  on  the  prominence 
in  bogs  of  the  sphagnum  mosses.  Allusion  has  also  been  made 
to  differences  in  the  ecological  relations  of  various  species,  in 
their  manner  of  growth,  and  in  the  role  which  they  play  in  bog 
development.  It  seems  appropriate  at  this  point  to  sum  up 
briefly,  with  reference  primarily  to  their  ecological  relations,  the 
essential  features  of  the  more  important  species  of  Sphagnum 
which-  grow  in  the  bogs  of  this  region.  These  may  be  divided 
more  or  less  definitely  into  five  groups,  as  follows. 

Group  i.  Plants  primarily  aquatic,  floating  at  or  near  the 
surface  of  the  water.  5".  cuspidatum:  commonly  yellowish 
green  in  color,  limp  and  flaccid,  with  a delicate,  feathery  appear- 
ance ; when  growing  emersed,  stems  usually  prostrate  and 
trailing  or  creeping.  The  var.  Torreyi  is  very  robust,  more 
rigid  than  the  typical  form,  and  ordinarily  a dirty  brownish 
green  in  color.  A.  Pylaisei:  dark  purple  to  nearly  black  in 
color;  soft  and  delicate,  but  as  a rule  scarcely  flaccid;  slender, 
with  sparsely  developed,  short  branches ; when  growing  emersed, 
stems  prostrate  and  trailing  or  semi-erect;  perhaps  the  most 
easily  recognized  of  any  native  sphagnum. 

Group  2.  Plants  semi-aquatic,  amphibious ; occasionally  com- 
pletely submerged  and  with  a habit  similar  to  that  of  S.  cuspida- 
tum, but  more  commonly  with  the  tips  of  the  shoots  projecting 
well  above  the  surface  of  the  water;  quite  robust,  fairly  rigid, 
erect.  S.  Dusenii:  in  color,  usually  green,  more  or  less  tinged 
with  y-dlow-brown.  S',  pulchrum:  in  color,  olive-green  to 

brownish  green ; commonly  grows  emersed,  forming  dense  but 
rather  loose,  soft  cushions  (see  further  under  group  4). 

Group  3.  Plants  primarily  non-aquatic,  commonly  growing  in 
low,  wet,  boggy  grounds.  S.  tenellum:  erect,  slender,  fragile, 
usually  occurring  in  dense,  loose  masses  and  forming  beautiful, 
soft,  low  mats;  in  color,  ordinarily  yellowish  green;  one  of  the 
most  delicately  lovely  of  all  the  sphagnums. 

Group  4.  Plants  mainly  non-aquatic,  though  commonly  grow- 
ing in  very  wet  places  and  occasionally  submersed ; usually  very 
robust,  erect  and  rather  rigid ; when  emersed,  forming  dense, 
rather  compact  masses  and  building  up  fairly  firm  cushions ; 
submersed  forms  quite  flaccid.  S.  papillosum:  in  color,  generally 


Vegetation  of  Northern  Cape  Breton.  423 

brownish  to  nearly  black.  6'.  magellanicum:  in  color,  pale 
greenish  white,  or  usually  strongly  tinged  with  pink  or  purple- 
red.  6\  pulchrum  might  perhaps  also  be  classed  here.  It  may 
be  noted,  as  of  contemporaneous  interest,  that  in  the  selection  of 
sphagnums  suitable  for  making  surgical  dressings  the  full-leaved 
forms  of  5’.  papillosum  and,  to  a lesser  extent,  S.  magellanicum 
have  been  found  to  furnish  the  best  material  (in  this  connection, 
see  Porter  ’17). 

Group  5.  Plants  strictly  non-aquatic,  growing  in  moist  or 
relatively  dry  situations ; erect  and  mostly  slender ; forming 
dense,  compact  masses  and  building  up  firm  cushions.  5". 
capillaceum  tenellum:  color  commonly  a vivid,  red.  S.  fuscnm: 
color  commonly  russet-green.  S',  tenerum:  color  commonly 

yellowish,  or  more  or  less  tinged  with  pink  or  red. 

As  grouped  above,  the  species  are  arranged  approximately  in 
the  order  of  decreasing  hydrophytism.  For  purposes  of  con- 
venience, the  species  of  group  1 may  be  referred  to  as  aquatic  or 
hydrophytic ; those  of  group  2 as  semi-aquatic ; those  of  group 
4 as  meso phytic;  and  those  of  group  5 as  xero phytic.  In  view 
of  their  tendency,  of  exceeding  importance  from  an  ecological 
standpoint,  to  form  more  or  less  compact  cushions,  the  species 
in  groups  4 and  5 may  be  distinguished  further  as  “cushion- 
forming species.”  The  significance  of  the  above  classification 
will  be  seen  presently. 

Outline  of  methods  by  which  bogs  arise  in  water-filled  depres- 
sions.— Bog  formation  in  water-filled  depressions  is  due  largely, 
if  not  wholly,  to  plant  activity.  In  general,  as  has  been  indicated 
elsewhere  (see  discussion  of  lowland  swamps),  there  y re  two 
methods  by  which  the  conversion  of  a pond  into  a swamp  may 
be.  accomplished.  These  may  be  designated:  (1)  filling  from 
within,  and  (2)  encroachment  from  without.  By  the  first 
method  the  bottom  of  the  pond  is  built  upward  toward  the  sur- 
face through  the  gradual  accumulation  thereon  of  successive 
layers  of  organic  debris,  derived  mainly  from  the  incompletely 
decomposed  remains  of  various  aquatic  plants.  By  the  second 
a mat  of  swamp  vegetation,  originating  on  the  banks  or  in  the 
shallow  water  near  the  shore,  pushes  outward  over  the  surface 
of_the  water,  roughly  speaking,  into  the  deeper  parts  of  the  pond. 
In  typical  instances  these  two  lines  of  development  are  quite 
distinct  from  one  another,  and  the  filling  in  of  a pond  may  be 


424 


George  E.  Nichols, 


accomplished  entirely  through  one  or  the  other.  But  both  pro- 
cesses may  commonly  be  observed  in  one  and  the  same  pond 
and,  as  will  be  shown  later,  the  filling  in  and  obliteration  of  the 
pond  may  frequently  be  achieved  through  the  combination  of 
the  two. 

Filling  from  within,  with  particular  reference  to  the  role  of 
various  sphagnums. — The  commonly  active  participation  in  this 
process  of  various  aquatic  seed  plants  and  algae  calls  for  no 
special  comment.  Of  more  interest  here  is  the  conspicuous  part 
often  taken  by  certain  species  of  sphagnum.  These  are  particu- 
larly important  in  the  barrens  where,  in  the  small,  undrained 
ponds  which  are  so  abundantly  developed  and  which  constitute 
such  a characteristic  feature  of  the  plateau,  various  sphagnums 
commonly  predominate  the  successive  stages  of  bog  evolution 
from  start  to  finish.  It  is  to  the  conditions  observed  in  and 
about  these  ponds  that  the  following  remarks  apply.  Here, 
while  a subordinate  part  may  frequently  be  played  by  various 
other  plants,  the  bulk  of  the  organic  debris  by  which  the  pond 
becomes  filled  in  up  to  water  level  is  contributed  by  the  two 
aquatic  sphagnums,  6\  Pylaisei  and  S.  cuspidatum,  associated 
with  which,  but  in  lesser  abundance,  usually  grows  the  liver- 
wort Cephalosia  fluitans.  During  the  summer  months  these  two 
species  of  Sphagnum,  either  or  both,  may  be  present  in  such  pro- 
fusion as  to  completely  clog  the  pond  to  a depth  of  several  inches 
below  the  surface  with  a loose,  floating  mass  of  vegetation.  One 
is  tempted  to  regard  such  a structure  as  a true  floating  mat, 
but  such  is  hardly  the  case  (see,  however,  in  this  connection, 
p.  429).  For  while  the  “mat”  does  float  during  the  growing 
season,  so  long  as  there  is  open  water  underneath  it  sinks  to  the 
bottom  in  winter.  It  is  indeed  extremely  doubtful  whether 
under  any  circumstances  sphagnum  of  itself  is  capable  of  form- 
ing a permanent  floating  mat,  i.  e.,  a raft-like  growth  sufficiently 
firm  and  stable  to  permit  the  establishment  and  maintenance  on 
its  surface  of  a non-aquatic  type  of  vegetation. 

Eventually,  however,  the  bottom  of  the  pond  may  become  built 
up  to  such  a level  that,  except  during  periods  of  high  water, 
the  substratum  is  exposed  to  the  air,  and  here,  in  addition  to  the 
bryophytes  which  have  been  largely  responsible  for  its  develop- 
ment and  which  still  cover  its  surface  with  a thin,  more  or  less 
continuous  mat,  the  soft,  mucky  ground  usually  becomes  popu- 


Vegetation  of  Northern  Cape  Breton. 


425 


lated  by  a very  characteristic  group  of  vascular  plants,  among 
which  the  following  are  almost  invariably  present : 


Ranunculus  Flammula  reptans  Utricularia  cornuta 

To  this  list  might  be  added  the  curly  grass  fern  (Schizaea) , 
which  sometimes,  and  the  bog  rosemary  ( Andromeda ),  which 
frequently  is  met  with  in  situations  of  this  sort.  An  important 
ecological  function  is  fulfilled  by  the  sedges  and  the  cranberries, 
since  through  the  medium  of  their  roots  and  stems  they  reinforce 
and  bind  together  the  mucky  deposit,  thereby  producing  a 
semblance  to  floating  mat  formation.  For  convenience,  a mat  of 
this  sort,  formed  over  a soft,  mucky  deposit,  may  be  referred  to 
as  a muck  mat. 

Sphagnums  of  the  semi-aquatic  group,  particularly  5". 
pulchrum,  frequently  put  in  an  appearance  while  the  rising  sub- 
stratum is  still  covered  by  some  depth  of  water.  In  such  cases 
the  succession  may  be  modified  to  such  a degree  that  the  muck 
mat  stage  is  omitted.  For  these  semi-aquatic  species,  growing 
in  fairly  dense  masses,  their  stems  erect  and  projecting  slightly 
above  water  level,  are  able  to  eliminate,  probably  through  the 
influence  of  shade,  the  lower,  more  truly  aquatic  sphagnums. 
Associated  with  the  sphagnums  in  such  a habitat  may  grow, 
locally  in  abundance,  Scheuchzeria,  Eleocharis,  Car  ex  limosa, 
Smilacina  trifolia  and  Menyanthes.  These  may  fulfill  here  a 
function  similar  to  that  performed  by  sedges  and  cranberry  in 
the  case  of  the  muck  mat,  where  also  they  are  not  infrequently 
represented. 

Returning  to  the  consideration  of  the  muck  mat : the  sphagnums 
of  the  aquatic  group  are  incapable  of  building  up  the  surface  to 
any  appreciable  height  above  ordinary  summer  water  level, 
although  to  a limited  extent  this  may  be  accomplished  by  the 
sedges.  Further  elevation  is  dependent  primarily  on  the  advent 
of  the  more  mesophytic  sphagnums.  For  some  reason,  the 
prostrate,  felty  tangle  of  aquatic  sphagnums  and  Cephalozia, 
which  commonly  covers  the  surface  of  the  muck  mat,  seems  to 
hinder  the  rapid  establishment  of  other  bryophvtes,  and  in 


Lycopodium  inundatum 
Rynchospora  alba 
Erio phorum  angustifolium 
Carex  oligosperma 


Drosera  longifolia 
Vaccinium  macrocarpon 
Vaccinium  Oxycoccus 
Bartonia  iodandra 


Trans.  Conn.  Acad.,  Vol.  XXII 


1918 


24 


426 


George  E.  Nichols, 


consequence  this  stage  may  be  protracted  for  a long  time.  But 
sooner  or  later  other  sphagnums  may  secure  a foothold  and 
eventually  gain  the  upper  hand. 

In  general,  the  elevation  of  the  bog  surface  above  water  level 
is  accomplished  very  largely  through  the  activity  of  species  of 
Sphagnum  which  possess  to  a more  or  less  marked  degree  the 
cushion-forming  habit,  but  the  process  is  greatly  facilitated  by 
the  concurrent  activity  of  the  vascular  plants  growing  on  the 
sphagnous  substratum,  since  these,  in  the  manner  already  sug- 
gested, bind  together  and  consolidate  the  sphagnum  cushions, 
and  in  addition  may  form  a sort  of  scaffolding  which  expedites 
the  upward  growth  of  the  mosses.  Sphagnum  pulchrum  with 
its  semi-aquatic  habit  is  a common  pioneer  on  the  muck  mat, 
and  with  its  erect  habit  of  growth  and  tendency  to  form  loose 
cushions  is  able  to  build  up  the  surface  to  some  height.  Fully 
as  important  at  this  stage,  and  subsequently  much  more  so,  are 
5\  papillosum  and  S',  magellanicum,  species  with  a generally 
more  robust  habit  and  a tendency  to  form  denser  cushions  than 
S.  pulchrum.  Any  of  these  three  species  may  act  as  pioneers, 
and  frequently  all  of  them  grow  intermixed. 

Once  the  cushion-forming  sphagnums  have  firmly  established 
themselves,  the  bog  surface  may  be  built  up  quite  rapidly.  A 
measure  of  the  rate  at  which  this  takes  place  is  sometimes 
afforded  by  shrubs  which  have  been  buried  by  the  rising  sub- 
stratum. To  cite  a specific  example,  in  an  erect  stem  of  Myrica 
Gale  which  had  been  partially  buried  to  a depth  of  eight  inches 
a discrepancy  of  seven  years  was  found  in  its  age  near  the 
bottom  of  the  deposit  (ten  years),  and  at  the  surface  (three 
years),  a fact  which  would  seem  to  indicate  that  here  the 
sphagnums  had  grown  upward  at  the  rate  of  about  an  inch  a year. 

As  the  surface  rises  higher,  the  mesophytic  sphagnums  (S. 
papillosum,  S.  magellanicum ) may  gradually  crowd  out  their 
more  hydrophytic  competitor  (S.  pulchrum).  The  height  to 
which  these  two  species  are  able  to  build  up  the  substratum 
varies,  being  apparently  conditioned  in  part  directly  by  soil 
moisture  relations,  but  largely  by  competition  on  the  part  of 
other  species.  For  with  its  increasing  elevation  the  substratum 
naturally  becomes  somewhat  drier  and  consequently  less  congenial 
to  the  mesophytic  species,  while  at  the  same  time  conditions 
become  more  favorable  for  relatively  xerophytic  species,  such  as 


Vegetation  of  Northern  Cape  Breton.  427 

.S'.  fuscum  and  5".  capillaceum  tenellum,  which,  while  they  may 
frequently  be  present,  do  not  thrive  in  the  wetter  situations. 
These  xerophytic  sphagnums,  at  first  growing  intermixed  with 
the  mesophytic  species,  gradually  become  more  abundant,  over- 
growing and  eventually  eliminating  their  less  xerophytic  competi- 
tors. The  mesophytic  cushion-forming  sphagnums  may  be 
largely  responsible  for  the  elevation  of  the  bog  surface  to  a 
height  of  a foot  or  two  above  the  original  water  level,  but  any 


Figure  62. — Margin  of  small  undrained  pond  near  crest  of  raised  bog; 
barrens  in  mountains  west  of  Ingonish;  in  foreground,  Andromeda  and 
other  shrubs  advancing  into  the  pool. 

further  upward  growth  is  dependent  very  largely  on  the 
xerophytic  cushion-forming  sphagnums,  which  invariably  are 
the  predominant  species  in  a mature  bog. 

Encroachment  from  without,  with  particular  reference  to  the 
formation  of  floating  mats. — In  its  essential  features,  floating 
mat  formation  in  the  highlands  differs  little  from  what  has  been 
described  for  the  lowlands.  The  pioneers  may  be  either  shrubs 
or  sedges.  In  the  former  case  (Fig.  62),  here  as  there,  unless 
the  framework  created  by  the  shrubs  becomes  overgrown  by 
sphagnums,  mat  formation  proceeds  no  farther  than  this  incipient 


428 


George  E.  Nichols , 


stage.  The  important  sphagnums  in  this  connection  are  5". 
pulchrum  and  the  more  mesophytic  cushion-forming  species,  but 
particularly  the  latter.  As  a rule  these  are  present  in  abundance, 
and  so  favorable  are  the  conditions  for  their  growth  here  in  the 
highlands  that  they  commonly  give  rise  to  a thick  mat  which 
rises  steeply  from  the  water’s  edge  to  a height  of  one  or  two 
feet.  Myrica  Gale,  Chamaedaphne,  and  Andromeda  are  all 
important  as  pioneer  shrubs,  now  one,  now  another  playing  the 
leading  role. 

Locally  certain  sedges  are  more  important  as  pioneers  in  mat 
formation  than  are  the  shrubs.  Carex  limosa  frequently  extends 
out  into  the  open  water  from  along  the  shore,  growing  in  length 
as  much  as  a foot  in  a single  season,  and  sometimes  it  is  present 
in  sufficient  abundance  to  form  the  basis  of  a mat.  More  com- 
monly Carex  filiformis  is  the  pioneer  sedge.  The  behavior  of 
this  species  in  mat  formation  has  been  described  by  Ganong 
(’03,  pp.  440-441),  Transeau  (’o5-’o6,  p.  363),  Davis  (’07, 
1 35— 1 38) , the  writer  (’15,  pp.  198-199),  and  others.  Commonly 
the  sedges  are  followed  by  the  sphagnums,  which  build  up  the 
surface  in  the  manner  already  described.  On  the  whole,  sedges 
are  much  less  prominent  in  the  role  of  mat  pioneers  than  are 
shrubs.  Moreover,  the  latter,  because  of  the  framework 
afforded  by  their  strong,  woody  stems,  favor  much  more  the 
growth  of  the  cushion-forming  sphagnums  and  the  consequent 
thickening  and  solidifying  of  the  mat. 

As  the  mat  grows  outward  into  the  pond,  the  open  water 
beneath  gradually  becomes  filled  in,  partly  by  the  sinking  of  the 
mat  as  it  becomes  thicker  and  heavier  through  the  continued 
upward  growth  at  its  surface,  partly  by  the  dropping  down  of 
vegetable  debris  from  the  under  surface  of  the  mat.  Where  the 
outward  growth  is  rapid,  the  mat  may  be  underlain  for  some 
distance  shoreward  from  its  outer  margin  by  open  water ; where 
outward  growth  is  slow  the  filling  in  beneath  may  keep  pace 
with  it,  so  that  very  little  of  the  mat  is  actually  floating.  But 
in  either  case,  wherever  the  filling  in  is  being  accomplished 
primarily  through  the  intervention  of  a floating  mat,  the  water 
in  the  pond  is  deep  right  up  to  the  edge  of  the  mat,  and  in  cases 
where  the  mat  has  become  “grounded”  clear  to  its  margin,  in 
the  manner  indicated  above,  the  bank  usually  sheers  precipitously 
to  the  bottom. 


Vegetation  of  Northern  Cape  Breton.  429 

A somewhat  puzzling  modification  in  floating  mat  formation 
is  exhibited  in  particular  by  many  of  the  small  ponds  in  the 
barrens.  Commonly  the  encroaching  banks  advance  at  a more 
or  less  uniform  rate  into  the  pond  from  one  or  several  sides,  but 
frequently  the  rate  of  advance  varies  locally,  and  to  such  an 
extent  that  the  marginal  bog  comes  to  project  out  into  the  pond 
in  triangular  or  tongue-shaped  masses  (Fig.  64).  Through  the 
continued  spread  or  coalescence  of  such  masses  a relatively  large 
pond  may  become  subdivided  into  several  smaller  ones : in  one 
case  noted  a group  of  nine  small  ponds  had  thus  originated. 
This  singular  behavior  is  not  correlated  with  any  differences  in 
the  depth  of  the  water,  and  for  a long  time  the  author  was  at 
a loss  for  an  explanation.  The  solution,  however,  appears  to  be 
somewhat  as  follows.  Attention  has  already  been  called  to  the 
fact  that  in  the  small,  undrained  ponds  of  the  barrens,  the  sur- 
face during  summer  is  commonly  occupied  by  a floating  mass 
of  aquatic  sphagnums.  In  winter  this  mass  sinks  to  the  bottom. 
Here  the  loose  tangle  may  become  intergrown  with  various  fila- 
mentous algae  to  such  an  extent  as  to  render  it  impervious  to 
gases,  and  the  following  spring  it  may  be  floated  toward  the 
surface  as  a result  of  gas  accumulation  underneath  or  within 
the  mass.  Cases  of  this  sort  have  been  frequently  noted.  As 
a rule,  only  portions  of  the  mass  actually  reach  the  surface,  and 
on  the  substratum  thus  presented  sedges  or  shrubs  may  gain  a 
foothold,  thus  inaugurating  what  essentially  is  a floating  mat. 
Very  often,  as  might  be  expected  if  this  explanation  is  correct, 
peninsulas  and  islands  of  bog  are  encountered  in  these  ponds. 
In  this  connection,  see  Powers’  paper  on  “Floating  Islands” 
(’14)- 

Encroachment  from  without  in  combination  with  filling  from 
within. — It  commonly  happens  that  the  conversion  of  a pond 
into  a swamp  is  accomplished  through  a combination  of  the  two 
methods  of  filling  just  described.  The  filling  in  up  to  the  sur- 
face level  may  be  due  largely  to  the  activity  of  aquatic  vegetation, 
and  it  is  on  the  substratum  thus  formed  that  the  mat  advances. 
In  this  connection  the  conditions  observed  around  a small,  name- 
less lake,  near  the  upper  limits  of  the  forested  region,  and  studied 
with  some  care  will  serve  as  an  illustration.  The  lake  covers  an 
area  of  perhaps  two  acres,  has  roughly  the  shape  of  a rounded 
equilateral  triangle,  and  is  drained  by  a small,  sluggish  stream. 


43° 


George  E.  Nichols, 


Its  original  size  has  been  reduced  about  one-half  by  the  centri- 
petal encroachment  of  the  bogs  which  now  surround  it  to  a 
variable  width  on  all  three  sides.  In  the  still  open  part  of  the 
pond,  the  bottom  seems  to  be  completely  covered  by  a soft,  mucky 
deposit  which  in  places  must  be  many  feet  thick.  This  deposit 
without  question  has  been  formed  almost  wholly  through  the 
accumulation  on  the  floor  of  the  pond  of  vegetable  debris,  which 
in  large  part  has  been  derived  from  the  remains  of  aquatic  seed 
plants,  mosses,  and  algae.  In  proceeding  from  the  middle  of 
the  lake  toward  the  shore,  the  depth  of  the  water  gradually 
diminishes,  the  mucky  bottom  sloping  gently  upward  until,  just 
before  the  lakeward  margin  of  the  bog  is  reached,  it  nearly  or 
actually  reaches  water  level.  On  the  substratum  thus  produced 
a mat  has  been  formed,  which  has  advanced  from  the  shore  out 
into  the  lake  as  rapidly  as  the  filling  in  process  has  permitted. 
And  in  this  connection  considerable  interest  attaches  itself  to  the 
divergent  courses  of  development  which  have  ensued  on  two  of 
the  three  sides  of  the  lake. 

Along  one  side  a sedge  mat  has  pushed  its  way  out  for  a 
distance  of  a dozen  or  fifteen  feet  from  the  original  shore.  For 
the  development  of  this  mat  three  plants  have  been  primarily 
responsible,  namely  Carex  filiformis,  Rynchospora  alba  and  R. 
fusca,  and  these  are  still  the  predominant  forms,  practically  the 
only  other  species  present  being  Utricularia  cornuta,  Drosera 
longifolia,  and  Sphagnum  Pylaisei.  The  mat  is  flat  and  firm, 
and,  although  it  is  but  a few  inches  above  ordinary  summer  water 
level,  one  can  walk  dry-shod  almost  to  its  edge. 

Along  the  other  shore  the  behavior  is  somewhat  different. 
The  shoal  water  along  the  margin  of  the  advancing  bog  is 
occupied  by  an  association  made  up  very  largely  of  the  mosses, 
Sphagnum  pulchruni  and  Drepanocladus  Sendtneri.  These  are 
present  in  sufficient  abundance  to  form  a low,  wet  substratum 
upon  which  the  sedges,  Carex  filiformis  and  Rynchospora  alba, 
together  locally  with  Andromeda,  gain  a foothold.  Thus  there 
is  formed  a low  mat  which  paves  the  way  for  further  progress. 
But  subsequent  development  is  not  always  the  same.  It  may 
follow  one  of  two  courses,  and  which  of  these  it  shall  be  seems 
to  depend  very  largely  on  which  species  of  Sphagnum  gains  con- 
trol over  the  situation.  Along  much  of  the  shore  papillosum 


Vegetation  of  Northern  Cape  Breton.  431 

establishes  itself  and  with  5".  pulchrum,  which  is  already  present, 
rapidly  builds  up  the  surface  to  a height  of  a foot  or  more  above 
water,  at  which  level  5".  fuscum  begins  to  assert  itself.  In  this 
way  there  arises  a typical  bog  (Fig.  63),  in  which  the  cushion- 
forming sphagnums  and  their  customary  vascular  associates  pre- 
vail. Locally,  however,  the  low  mat  is  usurped  by  Sphagnum 
Pylaisei.  This  sphagnum,  it  should  be  remarked,  while  it  grows 
profusely  in  many  small  undrained  ponds,  is  seldom  a conspicu- 


Figure  63. — A characteristic  bog  in  the  mountains  west  of  Ingonish : 
sedges,  ericads,  and  sphagnums  predominant,  with  scattered  clumps  of 
black  spruce. 

ous  element  of  the  aquatic  vegetation  in  ponds  of  any  size,  like 
the  present  one,  especially  where  they  are  well  drained.  But  it 
frequently  occurs  in  the  swamps  which  border  them.  Along 
with  5".  Pylaisei  commonly  grows  the  liverwort,  Cephalozia 
fluitans.  These  two  bryophytes,  as  elsewhere  suggested,  tend  to 
form  a rather  compact,  felty  growth  over  the  substratum,  which 
seems  in  some  inexplicable  manner  to  hinder  the  invasion  of 
these  areas  by  the  cushion-forming  sphagnums.  So  tenaciously, 
indeed,  may  they  hold  their  own  that,  as  the  contiguous  higher 


432 


George  E.  Nichols, 


portions  of  the  bog  push  out  into  the  pond,  these  lower  areas 
commonly  become  completely  engulfed.  The  vegetation  of  the 
hollows  thus  formed  is  strikingly  different  from  that  in  the  sur- 
rounding bog,  being  essentially  similar  to  that  of  the  muck  mat 
described  in  earlier  paragraphs.  In  addition  to  the  two  sedges, 
Carex  filiformis  and  Rynchosporci,  the  following  vascular  plants 
are  characteristic:  Schizaea  pusilla,  Lycopodium  inundatum, 

Carex  oligosperma,  Ranunculus  Flammula  reptans,  Drosera 
longifolia,  and  TJ tricularia  cornuta.  Ultimately  these  depressions 
seem  destined  to  become  incorporated  with  the  rest  of  the  bog, 
but  they  may  persist  virtually  unaltered  for  a long  time.  The 
usual  forerunner  of  the  typical  bog  vegetation  is  Scirpus 
caespitosus,  and  this  sedge  seems  to  pave  the  way  for  the 
tushion-forming  sphagnums  which  ultimately  gain  control. 

It  has  already  been  noted  that  in  the  small  ponds  of  the  bar- 
rens, where  the  aquatic  sphagnums  play  such  an  important  part 
in  the  filling  process,  the  mucky  substratum  which  these  form, 
with  its  felty  cover  of  Sphagnum  Pylaisei,  S.  cuspidatum,  and 
Cephalozia,  may  similarly  persist  virtually  without  further 
change  for  a very  long  time.  It  may  be  added  here  that  very 
commonly  such  areas  are  gradually  being  reduced  in  size  and 
seem  destined  to  extinction  through  the  slow  centripetal  encroach- 
ment of  the  steep,  peripheral  banks  of  sphagnum. 

The  method  of  filling  which  has  been  described  in  the  pre- 
ceding paragraphs  differs  from  that  previously  described  as  due 
entirely  to  “filling  from  within”  mainly  in  the  more  obvious 
centripetal  encroachment  of  the  marginal  swamp  vegetation.  As 
a matter  of  fact,  there  is  scarcely  any  real  distinction,  for, 
strictly  speaking,  as  soon  as  the  bottom  of  a pond  has  been 
built  to  the  surface  through  the  activity  of  the  aquatic  plants, 
any  further  changes  are  invariably  due  to  the  invasion  of  plants 
from  without. 

The  climax  association-type  of  bogs. — Extended  comment  is 
hardly  necessary.  The  character  of  the  climax  association-type 
varies  locally,  but  in  general  it  is  marked  by  the  predominance 
of  sphagnums  and  ericaceous  shrubs,  with  black  spruce  and 
tamarack.  In  many  cases  the  vegetation  of  ordinary  bogs  in 
the  highland  is  scarcely  different  from  that  described  for  low- 
land bogs,  while  in  others  it  closely  approximates  the  conditions 
found  in  raised  bogs  which  will  be  described  next. 


v 


4 33 


Vegetation  of  Northern  Cape  Breton. 

d.  THE  ASSOCIATION-COMPLEXES  OF  RAISED  BOGS 

Geographical  distribution  of  raised  bogs  in  eastern  North 
America. — Bogs  of  the  raised  ( “Hochmoor ”)  type  (Figs.  64,  66) 
are  extensively  developed  in  parts  of  northern  Europe,  and  there 
are  numerous  published  accounts  dealing  with  them,  both  from 
an  economic  and  a biological  standpoint.  But  concerning  their 
occurrence  and  distribution  in  North  America  little  is  known, 
and  specific  references  to  them  in  the  literature  are  scarce. 


Figure  64. — Raised  bog  on  Peter’s  Barren,  in  the  mountains  east  of 
Frizzleton;  in  the  foreground,  pond  and  low,  wet  bog;  in  the  background, 
the  more  elevated  part  of  the  bog,  which  rises  more  than  twelve  feet  above 
the  pond  level. 

Ganong,  more  than  twenty-five  years  ago  (’91),  called  attention 
to  the  presence  in  New  Brunswick  of  bogs  of  this  type,  and  in 
1898  he  published  a rather  detailed  account  of  the  raised  bogs  in 
the  southern  part  of  this  province.  He  has  also  made  some  brief 
notes  (’o6b)  on  the  raised  bogs  of  Miscou  Island,  New  Bruns- 
wick. In  his  second  paper,  Ganong  indicates  the  reported 
occurrence  of  raised  bogs  in  Nova  Scotia  and  Anticosti,  and  the 
probability  of  their  occurrence  in  Newfoundland.  In  a recent 


434 


George  E.  Nichols, 


publication  (’15),  the  third  of  a series  of  papers  on  the  economic 
aspects  of  peat  bogs  of  Canada,  Anrep,  speaking  of  the  Clyde 
Peat  Bog  in  Nova  Scotia,  states  (p.  55)  that  “this  is  the  first 
‘high  moor’  bog  encountered  during  the  last  six  years  of  inves- 
tigation” (a  period  during  which  he  had  studied  numerous  bogs 
in  Manitoba,  Ontario,  and  Quebec).  Davis,  in  discussing  the 
origin  of  the  Maine  peat  deposits  (Bastin  & Davis,  ’09),  gives 
a short  description  of  the  manner  in  which  raised  bogs  are 
formed  and  -of  the  relation  between  “built-up  deposits”  and 
“filled-basin  deposits.”  The  former,  corresponding  to  the  raised 
bog,  appears  to  be  a not  infrequent  type  of  swamp  along  the 
Maine  coast  as  far  south  as  the  vicinity  of  Portland,  and  evi- 
dently it  is  of  quite  common  occurrence  northeastward.  On  the 
whole,  judging  from  the  data  at  hand,  both  published  and  unpub- 
lished, it  would  appear  that  in  eastern  North  America  raised  bogs 
are  largely  confined  to  Newfoundland  and  to  those  parts  of 
eastern  Canada  and  Maine  which  are  in  the  proximity  of  the 
sea-coast.  Their  limitation  to  this  region  is  unquestionably 
correlated  with  the  character  of  the  climate:  the  abundant 

precipitation,  relatively  low  atmospheric  humidity,  cool  summers, 
and  the  absence  of  extreme  low  winter  temperatures  such  as 
prevail  farther  inland.  The  paucity  of  literature  dealing  with 
raised  bogs  in  this  country  is  doubtless  attributable,  as  Ganong 
suggests,  to  their  remoteness  from  botanical  centers  and  their 
hitherto  little  appreciated  economic  value.  In  Europe,  “great 
bogs  occur  within  easy  reach  of  the  botanists  of  Germany,  Swit- 
zerland, and  Scandinavia,  and  their  great  economic  value  has 
led  to  their  exhaustive  study  both  by  individual  workers  and  by 
government  commissions”  (’98,  p.  131). 

From  the  brief  examination  which  the  author  was  able  to 
make  of  the  Spruce  Lake  bog  and  two  neighboring  smaller  bogs 
about  a dozen  miles  west  of  St.  John,  New  Brunswick,  it  may 
be  stated  that  the  raised  bogs  of  this  region,  as  described  by 
Ganong,  are  essentially  similar  to  those  of  northern  Cape  Breton. 

Occurrence  of  raised  hogs  in  northern  Cape  Breton. — In  this 
particular  region  raised  bogs  apparently  are  confined  to  the 
plateau,  but  this  is  very  likely  due  to  edaphic  rather  than  atmos- 
pheric factors,  since  in  southeastern  Cape  Breton  fine  raised  bogs 
occur  at  but  little  above  sea-level.  On  the  highlands  in  northern 
Cape  Breton  raised  bogs  are  encountered  here  and  there  in  the 


Vegetation  of  Northern  Cape  Breton.  435 

forested  region,  but  their  greatest  display  is  seen  in  the  barrens. 
To  the  study  of  the  origin,  development  and  ecological  relations 
of  the  raised  bogs  here  the  author  has  devoted  considerable 
time,  and  it  is  hoped  that  the  facts  set  forth  in  the  following 
pages  may  contribute  materially  to  the  knowledge  of  this 
fascinating  swamp  type,  as  developed  on  this  continent. 

General  features  of  raised  bogs  and  the  influence  of  edaphic 
factors  on  their  local  distribution. — The  most  bizarre  feature  of 
a raised  bog  is  the  fact  that  it  is  higher  toward  the  center  than 
toward  the  margin : the  surface  is  convex,  and  the  entire 

structure  frequently  presents  more  or  less  the  form  of  an  inverted 
saucer  or  watch-glass.  The  outline  of  a typical  raised  bog,  as 
viewed  in  cross  section,  is  shown  by  Fig.  65,  B.  In  this  connec- 
tion, it  might  be  remarked  that  a slight  convexity  in  the  contour 
of  the  surface  is  perceptible  in  some  of  the  lowland  bogs  of 
northern  Cape  Breton,  and  similar  conditions  are  occasionally 
noted  in  southern  New  England;  but  in  these  cases  the  eleva- 
tion of  the  middle  portions  at  most  is  only  a foot  or  two.  In 
the  case  of  typical  raised  bogs  the  difference  in  height  between 
margin  and  center  may  be  many  feet : viewed  from  the  surface 
alone,  and  disregarding  the  contour  of  the  underlying  rock  floor, 
the  higher  portion  may  rise- to  a height  of  from  fifteen  to  twenty 
or  more  feet  above  the  lower  marginal  portions.  But  that  the 
actual  elevation  of  the  bog  surface  above  the  rock  substratum 
in  reality  is  often  much  less  than  it  appears  from  superficial 
examination  will  be  apparent  later.  As  shown  by  the  cross 
section  (Fig.  65,  C,  f-h ) the  surface  rises  rather  abruptly  from 
near  the  margin,  then  more  gently,  and  the  top  of  the  bog  may 
be  practically  flat.  The  angle  of  slope  along  the  steeper  flanks 
of  a bog  varies  locally,  but  ordinarily  the  surface  rises  at  the 
rate  of  about  one  foot  to  fifteen  or  twenty  on  the  level.  Some- 
times, however,  the  slope  is  much  steeper:  in  one  extreme 

instance  (foreground  of  Fig.  64),  for  example,  a rise  of  three 
feet  in  three  and  six  feet  in  twelve  was  noted.  The  bogs  vary 
in  size,  but  commonly  they  are  many  acres  in  extent,  and  in  some 
cases  they  stretch  out  uninterruptedly  for  more  than  a mile.  On 
the  higher  levels  of  the  bog  the  ground  underfoot,  for  the  most 
part,  is  quite  firm  and  springy,  but  locally,  particularly  in  the 
vicinity  of  the  small  ponds  which  are  frequently  present,  it  may 
be  soft  and  spongy.  The  character  of  the  surface  vegetation 


4 36 


George  E.  Nichols, 


will  be  discussed  in  detail  later:  suffice  it  to  state  here  that  in 
addition  to  the  sphagnums  which  form  the  groundwork  of  the 
mass,  the  most  prominent  plants  are  low,  ericaceous  shrubs  and 
the  sedge,  Scirpus  caespitosus. 

For  the  development  of  a raised  bog,  the  fundamental  pre- 
requisites are  the  presence  of  certain  species  of  sphagnum  and 
of  environmental  conditions  congenial  to  their  growth,  since 
from  start  to  finish  in  the  evolution  of  such  a bog  these  mosses 
play  an  all  essential  role.  Of  foremost  importance  is  a copious 
water  supply,  and  this  is  controlled  partly  by  climatic,  partly  by 
edaphic  conditions.  Of  the  water  which  falls  on  the  earth’s 
surface  in  the  form  of  rain  and  snow,  part  enters  the  ground, 
forming  the  ground  water  supply ; part'  runs  off  over  the  surface 
into  streams  and  lakes ; the  remainder  is  evaporated  or  is 
absorbed  directly  by  vegetation.  In  so  far  as  the  development 
of  raised  bogs  is  concerned,  it  is  now  generally  recognized  that 
the  chief  source  of  their  water  supply  is  meteoric,  rather  than 
telluric.  In  other  words,  while  locally  a limited  amount  of  the 
water  needed  may  be  derived  from  springs,  on  the  whole  their 
distribution  and  growth  is  independent  of  the  ground  water 
supply.  Surface  drainage  from  neighboring  slopes  may  and 
frequently  does  help  out,  but  in  the  large  it  is  the  water  pre- 
cipitated directly  upon  the  surface  of  the  area  occupied,  in  the 
form  of  either  rain  or  snow,  which  is  most  important.  Swamps 
which  thus  are  dependent  directly  upon  atmospheric  precipitation 
for  their  water  supply  have  been  designated  precipitation-swamps, 
by  way  of  distinction  from  spring-swamps  and  lake-swamps  (see 
earlier  remarks,  p.  354). 

The  importance  of  edaphic  factors  is  seen  in  their  influence 
on  water  loss  through  surface  runoff  and  downward  percola- 
tion. Given  a substratum  sufficiently  impermeable  to  prevent  loss 
through  percolation,  a raised  bog  may  originate  under  quite 
varied  topographic  conditions.  In  general,  it  may  be  built  up 
either  in  and  around  a water-filled  rock  basin  or  over  any 
essentially  flat,  undulating  or  irregular  surface  from  which  the 
rain  and  snow  water  tend  to  run  off  slowly  or  to  accumulate  in 
local  depressions.  Such  surfaces  as  the  latter,  considered  in 
their  entirety,  may  be  either  approximately  level  or  slightly 
inclined.  It  is  probably  the  lack  of  suitable  areas  of  impermeable 
substratum  that  is  responsible  for  the  observed  absence  of  raised 


Vegetation  of  Northern  Cape  Breton. 


437 


bogs  in  the  lowland.  In  the  highland  the  substratum  underlying 
the  raised  bogs  is  practically  impervious  granite  rock,  bare,  or 
thinly  covered  by  a gravelly  soil. 


Figure  65. — Diagrammatic  representation  of  a bog  complex  in  the  bar- 
rens; see  text.  A.  Sketch  map  showing  relation  of  area  to  adjoining 
upland.  B.  & C.  Longi-sections  along  line  a-i  on  map.  Section  A 
drawn  to  scale ; in  section  B,  vertical  scale  eight  times  the  horizontal,  and 
contour  of  rock  floor  indicated  by  dotted  line.  All  measurements  in  feet. 
Arrows  indicate  location  of  soundings.  Mountains  west  of  Ingonish. 


438 


George  E.  Nichols, 


a.  Development  of  Raised  Bogs  in  and  around  Water-filled 

Rock  Basins 

An  illustrative  example. — In  Fig.  65  is  represented  diagram- 
matically  a bog-complex  which  was  studied  in  some  detail. 
Depth  of  peat,  surface  contour,  and  relations  of  the  underlying 
topography  were  determined  by  means  of  sounding-rod  and 
level.  Section  B,  made  along  the  line  a-i  in  map  A,  is  drawn  to 
scale  and  shows  the  actual  contour  of  the  surface.  Section  C, 
identical  with  Section  B but  with  the  vertical  scale  eight  times 


Figure  66. — Raised  bog  in  barrens,  mountains  west  of  Ingonish;  photo- 
graph taken  from  point  between  d and  e in  Fig.  65.  In  foreground,  wet 
bog ; figures  standing  on  dry  bog ; see  text. 


the  horizontal,  brings  out  the  relation  between  the  surface  con- 
tour and  that  of  the  rock  floor  beneath.  It  will  be  seen  from 
this  diagram  (f-i,  etc.)  that  the  upper  portion  of  the  bog-complex 
(the  portion  pictured  in  Fig.  66)  is  occupied  by  a typical  raised 
bog,  which  has  been  developed  in  and  around  a shallow  rock- 
basin.  Through  the  accumulation  of  peat,  the  surface  has  been 
built  up  more  than  six  feet  above  the  rim  of  the  basin  and  about 
ten  feet  above  its  bottom,  and  has  spread  out  over  the  rim. 
Attention  may  now  be  given  to  the  manner  in  which  this  bog 


Vegetation  of  Northern  Cape  Breton.  439 

has  been  formed,  the  lower  portion  of  the  complex  (Fig.  65,  C, 
a-f ) being  neglected  for  the  moment. 

The  rock  basin  in  question  is  situated  at  the  summit  of  a low, 
rounded  hillock  which  is  bounded  laterally  by  slightly  higher 
hills.  Partly  as  the  result  of  direct  precipitation,  partly  perhaps 
through  surface  drainage  from  the  adjoining  higher  ground, 
this  basin  originally  was  kept  filled  with  water,  which  spilled  out 
over  the  rim  at  g.  The  manner  in  which  this  pond  became 
obliterated  was  doubtless  similar  to  what  has  been  described  in 
the  general  discussion  of  bogs  a few  pages  back.  The  open 
water  ma)-  have  become  filled  in  through  the  activity  of  the 
aquatic  sphagnums,  or  through  the  encroachment  from  the 
margin  of  a floating  mat,  or  through  a combination  of  both 
these  methods.  Assuming  the  aquatic  sphagnums  to  have  been 
the  pioneers,  and  that  through  their  activity  the  pond  had  been 
more  or  less  completely  clogged  up,  the  second  stage  in  the  suc- 
cession was  probably  dominated  by  the  mesophytic  cushion- 
forming species  (S.  papillosum,  S.  magellanicum,  S.  pulchrum ), 
although  there  may  have  been  an  intermediate  stage  of  semi- 
aquatic  species  (S.  pulchrum,  S.  Dusenii).  Largely  through  the 
activity  of  the  mesophytic  cushion-forming  sphagnums  the  sur- 
face may  have  been  raised  to  a height  of  one  or  two  feet  above 
the  former  pond  surface,  at  which  point  the  xerophytic  cushion- 
forming species  (5".  fuscum,  S.  capillaceum  tenellum,  S. 
tenerum ) asserted  themselves.  It  is  to  the  species  of  this  latter 
group  that  the  further  elevation  of  the  bog  surface  to  its  present 
height  has  been  largely  due.  Throughout  this  series  of  changes, 
various  seed  plants  have  occupied  a more  or  less  prominent 
position,  and  have  played  an  important  role  by  binding  together 
and  strengthening  the  ground-work  formed  by  the  sphagnums. 
The  stages  characterized  by  the  predominance  of  the  mesophytic 
and  of  the  xerophytic  sphagnums  may  be  designated  respectively 
the  wet  bog  and  the  dry  bog  stages.  The  character  of  the  sur- 
face vegetation  in  these  two  stages  will  be  described  later. 

General  observations. — The  exact  stage  at  which  the  central 
water  body  becomes  obliterated  in  successions  of  the  sort  just 
described  varies.  In  the  present  case,  the  pond  has  been  over- 
whelmed so  completely  that  there  is  absolutely  nothing  on  the 
surface  of  the  bog  that  even  suggests  its  former  presence.  In 
other  cases,  however,  the  pond  may  persist  for  an  indefinite 


44° 


George  E.  Nichols, 


period,  and  may  even  be  present  on  the  higher  parts  of  the 
mature  bog.  The  factors  concerned  may  be  various,  but  of 
particular  importance  seem  to  be  the  depth  of  the  basin  to  start 
with  and  the  luxuriance  with  which  the  aquatic  sphagnums 
develop.  Where  these  latter  are  absent  or  poorly  represented,  so 
that  the  filling  in  is  dependent  on  encroachment  from  the  margin, 
the  elimination  of  the  pond  proceeds  slowly.  For  while  the 
mesophytic,  cushion-forming  sphagnums  may  grow  luxuriantly, 
forming  great  banks  of  vegetation  around  the  edge  of  the  pond, 
the  centripetal  advance  into  the  pond  of  the  fringing  banks  is 
usually  slow.  For  this  latter  fact  the  commonly  sparse  develop- 
ment of  the  pioneer,  skeleton-forming  shrubs  seems  primarily 
responsible,  since  wherever  an  adequate  shrubby  framework  is 
presented  the  sphagnums  tend  to  push  out  from  the  shore  quite 
rapidly.  The  banks  of  sphagnum  commonly  come  to  form  a 
complete  circle  about  the  pond  and  block  up  any  natural  outlet 
which  may  have  existed.  (Of  course,  in  the  case  of  spring-fed 
ponds  or  of  any  ponds  with  a considerable  outflow,  the  outlet 
may  not  become  completely  dammed,  but  such  ponds  are  rarely 
concerned  here  in  the  development  of  raised  bogs.)  Thereafter 
drainage  must  be  accomplished  entirely  by  slow  seepage  through 
the  peaty  banks.  As  these  banks  are  built  up  higher  through 
the  growth  of  the  sphagnums  at  the  surface,  the  peat  underneath 
becomes  more  and  more  compressed  by  the  superimposed  weight 
and  in  consequence  less  and  less  permeable.  The  result  is 
obvious : as  the  drainage  becomes  impeded  below,  the  surface 
of  the  pond  is  forced  to  a higher  level,  and  in  this  way,  as  fast 
as  the  surface  of  the  bog  is  built  upward,  the  pond  likewise  is 
shoved  higher  and  higher,  until  ultimately  it  may  come  to  lie  at 
the  crest  of  the  mature  bog.  Concurrently  with  the  changes 
just  outlined,  the  bottom  of  the  pond  may  likewise  be  built  up 
through  filling  from  within,  but  only  when  this  latter  process 
proceeds  at  a more  rapid  rate  than  that  at  which  the  surface 
of  the  pond  rises  can  it  have  any  immediate  visible  effect. 

Mention  has  been  made  earlier  of  the  convex  surface  which 
is  possessed  to  a greater  or  less  degree  by  all  raised  bogs.  This 
convexity  is  most  pronounced  in  bogs  like  the  one  just  described, 
where  there  is  a central  pond  which  acts  as  a reservoir  and  from 
which  water  seeps  out  in  all  directions.  It  is  self-evident  that 
the  areas  nearest  the  pond  will  be  best  watered : it  is  here  that 


Vegetation  of  Northern  Cape  Breton.  441 

the  sphagnums  thrive  most  luxuriantly  and  grow  most  rapidly 
and  that  the  surface  of  the  bog  tends  to  be  built  up  the  fastest 
and  to  the  greatest  height.  Farther  away  from  the  pond,  at 
least  during  dry  spells,  the  water  supply  is  less  abundant,  so  that 
the  "rate  of  upward  growth  is  slower  and  the  height  limit  lower 
than  in  the  more  favorable  central  portions.  The  conditions, 
however,  are  not  always  as  simple  as  are  here  suggested. 
Especially  are  complexities  introduced  through  the  development 
of  ponds  which  are  a result  rather  than  a primary  cause  of  bog 
development.  Ponds  of  this  “subsequent”  type,  as  will  be  shown 
presently,  are  even  more  generally  associated  with  raised  bogs 
than  are  ponds  of  the  “antecedent”  type,  like  those  just  described. 

/?.  Development  of  Raised  Bogs  over  Flat  or  Irregularly 
Undulating  Rock  Surfaces 

Perhaps  more  commonly  than  not,  in  northern  Cape  Breton, 
the  rock  floor  which  underlies  a raised  bog  is  essentially  flat  or 
else  irregularly  undulating:  at  any  rate  there  are  no  rock  basins 
capable  of  holding  any  appreciable  amount  of  Avater.  In  the 
development  of  raised  bogs  in  situations  of  this  description, 
three  more  or  less  definite  stages  can  frequently  be  distinguished, 
which  may  be  designated  respectively  the  Bog  Meadow  stage,  the 
Wet  Bog  stage,  and  the  Dry  Bog  stage.  Owing  largely  to  local 
variations  in  topography,  the  rate  at  which  bog  formation  has 
progressed  and  the  degree  to  which  the  raised  bog  climax  has 
been  approached  varies  greatly.  All  stages  in  the  succession, 
which  under  favorable  conditions  culminates  in  the  formation  of 
the  typical  raised  bog  association-type,  may  be  found,  and, 
locally,  any  of  the  three  types  just  mentioned  may  constitute  an 
edaphic  climax.  Through  the  study  and  comparison  of  a large 
number  of  such  areas,  the  general  course  or  courses  of  develop- 
ment and  the  ecological  relations  of  the  association-types  involved 
have  been  quite  satisfactorily  worked  out.  In  the  following 
account,  attention  is  first  directed  to  the  chief  features,  vege- 
tational  and  otherwise,  of  the  respective  stages,  after  which  their 
relation  to  one  another  and  to  bog  development  will  be  discussed. 

The  hog  meadow  association-type. — As  stated  earlier,  the  sur- 
face of  the  tableland  comprises  a series  of  low,  rounded  hills, 
which  rise  to  a rather  uniform  height  and  are  separated  by 


442 


George  E.  Nichols, 


valleys  of  varying  depth,  but  mostly  shallow.  Many  of  these 
valleys  (Fig.  67)  are  quite  broad,  with  a nearly  flat  or  slightly 
trough-shaped  floor,  and  lie  but  little  below  the  general  level  of 
the  surrounding  low  hills.  Lengthwise  the  floor  may  be  nearly 
level,  but  commonly  it  slopes  gently  in  one  direction  or  another. 
The  ground  here  for  the  most  part  is  well  watered,  not  only  by 
direct  precipitation  but  by  surface  drainage  from  the  higher 
slopes.  It  is  in  situations  of  this  sort  that  the  bog  meadow 
association-type  is  best  developed. 


Figure  67. — Broad,  shallow  valley  in  barrens;  mountains  west  of  Ingo- 
nish ; occupied  mainly  by  wet  bog,  but  partly  by  bog  meadow.  In  the 
background,  low  hills  covered  with  forest  scrub. 


The  outstanding  characteristics  of  bog  meadow  are  as  follows. 
The  predominant  vegetation  is  grass-like,  being  made  up  chiefly 
of  Scirpus  caespitosus  and  Calamagrostis  Pickeringii,  with 
Rynchospora  alba  locally  prominent.  These  plants  form  a thin, 
more  or  less  continuous  sward.  Woody  plants  are  relatively 
inconspicuous,  but  there  is  always  a scattered  growth  of  low 
shrubs,  mainly  Myrica  Gale,  Andromeda,  and  Chamaedaphne, 
which  rise  scarcely  higher  than  the  sedges,  while  the  tamarack 
commonly  is  represented  by  occasional  small  stunted  specimens. 


Vegetation  of  Northern  Cape  Breton. 


443 


The  cushion-forming  species  of  sphagnum  are  usually  incon- 
spicuous, although  the  substratum  beneath  the  grasses  and  sedges 
is  commonly  carpeted,  at  least  locally,  with  Sphagnum  Pylaisei 
and  5".  tenellum,  together  with  the  liverwort,  Cephalozia  fluitans. 
The  g'round  is  covered  by  a firm  turf,  beneath  which  there  usually 
is  a layer  of  peat  from  a few  inches  to  a couple  of  feet  in  depth. 
The  peat  is  quite  compact,  consisting  very  largely  of  the  remains 
of  sedges  and  grasses,  but  usually  with  a matrix  of  sphagnum 
remains.  The  surface  of  the  swamp  is  flat  or  undulating;  it 
is  relatively  smooth,  and  not  hummocky.  Slight  depressions  in 
the  substratum  are  frequent,  and  in  some  of  these  water  may 
accumulate  temporarily  to  the  depth  of  a few  inches,  but  there 
are  few  if  any  ponds  of  the  sort  to  be  described  as  characteristic 
of  wet  bogs.  In  addition  to  the  three  shrubs  named  above, 
Kalmia  polifolia,  Vaccinium  macrocarpon,  and  V.  Oxycoccus  are 
commonly  present,  the  two  latter,  as  well  as  the  species 
starred  (*)  in  the  subjoined  list,  being  more  characteristic  of  the 
depressions,  particularly  where,  as  is  commonly  the  case, 
Splvignum  Pylaisei  and  Cephalozia  form  a more  or  less  con- 
tinuous, felty  ground  cover.  Additional  herbaceous  vascular 
plants  commonly  met  with  in  bog  meadows  are  as  follows : 


Schizaea  pusilla* 
Lycopodium  inundatum * 
Eriophorum  virginicum 
Carex  oligosperma* 
Carex  exilis 
Habenaria  clavellata 
Sarracenia  purpurea 


Drosera  longifolia* 
Drosera  rotundifolia* 
Bartonia  iodandra* 
Utricularia  cornuta* 
Solidago  uliginosa 
Aster  nemoralis 
Aster  radula 


The  vegetation  of  the  shallow  depressions  just  referred  to 
should  perhaps  be  regarded  as  constituting  a distinct  association- 
type,  but  for  convenience  they  are  included  here  merely  as  a type 
of  society. 

The  wet  bog  association-type. — This  is  commonly  developed 
in  situations  similar  to  those  indicated  for  the  preceding  type, 
but  conditions  are  most  favorable  where  the  surface  slope  is  slight 
and  where  the  presence  of  shallow  depressions  or  approximately 
horizontal  surfaces  affords  habitats  which  are  congenial  to  the 
local  growth  of  the  mesophytic  cushion-forming  sphagnums. 
The  influence  of  topography  is  suggested  by  diagram  C of  Fig. 


444 


George  E.  Nichols, 


65,  where  area  a-e  is  occupied  by  wet  bog,  and  area  e-f  by  bog 
meadow.  Frequently,  as  here,  the  two  types  of  swamp  alter- 
nate on  the  same  slope,  while  very  commonly  the  wet  bog  which 
occupies  the  floor  of  a shallow  valley  (Fig.  67)  is  separated  from 
the  typical  upland  vegetation  on  either  flank  by  strips  of  bog 
meadow. 


Figure  68. — In  foreground,  wet  bog  association-type  (same  area  as  that 
shown  by  Fig.  67),  with  pools  due  to  activity  of  sphagnum  (see  text) ; in 
background,  low  hill  covered  with  forest  scrub ; barrens  in  mountains 
west  of  Ingonish. 

So  far  as  the  vascular  element  in  the  vegetation  is  concerned, 
the  chief  difference  between  this  and  the  preceding  association- 
type  is  seen  in  the  relatively  greater  abundance  here  of  the  shrubs. 
Essentially  the  same  list  of  seed  plants  is  characteristic  of  each 
swamp  type,  and  both  shrubs  ( Andromeda , Myrica,  Chamae- 
daphne,  Vaccinium  Oxycoccus,  etc.)  and  herbaceous  plants 
( Scirpus , Rynchospora,  Eriophorum , etc.)  are  well  represented 


Vegetation  of  Northern  Cape  Breton.  445 

here.  The  following  additional  species  might  be  mentioned  as 
characteristic  of  wet  bogs,  although  they  may  also  occur  to 
some  extent  in  bog  meadows : Eriophorum  callitrix,  E.  angusti- 
folinm,  Carex  paucifiora,  C.  paupercula,  Smilacina  trifolia. 
Beside  these,  various  of  the  species  of  dry  bogs,  not  yet  men- 
tioned, may  be  sparingly  represented.  But  the  vascular  plants 
are  of  subordinate  importance  to  the  sphagnums,  and  the  funda- 
mental dissimilarity  between  the  vegetation  of  wet  bog  and  that 
of  bog  meadow  lies  in  the  predominance  here  of  these  mosses. 
Foremost  among  the  sphagnums  are  the  mesophytic  cushion- 
forming species  (S.  papillosum,  S.  magellanicum,  and  S. 
pulchrum).  Growing  in  rich  profusion,  these  latter  form  soft, 
wet,  cushion-like  or  pillow-like  beds  which  cover  the  ground 
almost  uninterruptedly  over  large  areas.  Other  species  of 
Sphagnum,  however,  are  by  no  means  absent.  Hollows  in  the 
bog  proper  are  commonly  occupied  by  societies  of  5".  tenellum  and 

Pylaisei,  species  which  do  not  form  cushions,  while  on  the 
higher  cushions,  in  greater  or  less  abundance,  may  grow  the 
relatively  xerophytic  cushion-forming  species.  In  addition,  the 
small  ponds  or  pools  which  commonly  dot  the  bog  surface  (Figs. 
62,  64,  66,  68,  69)  usually  contain  various  aquatic  and  semi- 
aquatic  species.  These  ponds  constitute  one  of  the  most  dis- 
tinctive features  of  areas  occupied  by  wet  bog,  but  their  vege- 
tation, strictly  speaking,  belongs  in  quite  a different  category 
from  that  of  the  wet  bog  association-type  (see  further  under  dis- 
cussion of  successional  relations). 

The  surface  of  a wet  bog,  viewed  in  its  entirety,  may  be  flat 
or  slightly  convex;  viewed  in  detail  it  is  more  or  less  uneven 
and  hummocky.  It  is  commonly  underlain  by  an  accumulation 
of  peat  from  two  to  four  feet  in  thickness,  which  consists  of  an 
intimate  admixture  of  sphagnum,  sedge,  and  shrub  remains. 

The  dry  bog  association-type. — This,  the  culminating  associa- 
tion-type of  the  raised  bog  series,  may  develop  in  similar  situa- 
tions to  the  preceding  but  particularly  or  nearly  level  surfaces, 
either  flat  or  undulating.  In  contrast  to  bog  meadow  and  wet 
bog,  perhaps  the  most  striking  features  of  a dry  bog  (Figs.  66, 
69)  are  its  usually  convex  shape,  the  luxuriant  development  of 
the  xerophytic  cushion-forming  sphagnums  (S.  fuscum,  S. 
capillaceum  tenellum  and  6'.  tenerum ),  the  presence  of  such 
xerophytic  seed  plants  as  Empetrum,  Gaultheria,  and  Vaccinium 


446 


George  E.  Nichols, 


pennsylvanicum,  and  the  predominance  among  the  vascular  plants 
of  ericaceous  shrubs.  The  bake  apple  ( Rubus  Chamaemorus ) 
is  one  of  the  most  characteristic  plants  of  dry  bogs.  The  sur- 
face of  such  a bog  is  hummocky,  and  except  in  wet  weather 
the  springy  substratum  underfoot  is  quite  dry.  The  hummocks 
vary  from  one  to  several  feet  in  diameter  and  from  a few  inches 
to  more  than  a foot  in  height.16  The  depth  of  peat  ranges  up 
to  more  than  six  feet  over  a flat  rock  floor,  while  over  depres- 
sions it  may  be  considerably  greater.  Pools  of  the  sort  charac- 
teristic of  wet  bogs  are  found  here  also,  but  much  less 
abundantly.  Except  for  these  and  scattered  wet  depressions, 
whose  vegetation  and  ecological  relations  are  quite  distinct  from 
those  of  the  enveloping  area  of  dry  bog  (see  later),  the  surface 
almost  everywhere  is  overgrown  by  the  xerophytic  cushion- 
forming sphagnums,  associated  with  which,  and  locally  pre- 
dominant, are  certain  other  mosses  (such  as  Dicranum  Bergeri, 
Racomitrium  lanuginosum,  and  Poly  trichum  juniperinum ) and 
fruticose  lichens  (notably  Cladonia  alpestris,  C.  sylvatica,  and 
Cetraria  islandica).  The  moist  hollows  between  the  hummocks 
are  commonly  colonized  very  largely  by  liverworts,  such  species 
as  Ptilidium  ciliare,  Cephalozia  media,  Lepidozia  setacea,  and 
Mylia  anomala,  which  constitute  more  or  less  definite  societies. 
The  characteristic  vascular  plants  of  the  dry  bog  association- 
type  are  the  following: 


Picea  mariana 
Larix  laricina 
Eriopliorum  callitrix 
Scirpus  caespitosus 
Carex  pauciflora 
Myrica  Gale 
Sarracenia  purpurea 
Drosera  rotundifolia 
Pyrus  arbutifolia  atropurpurea 
Rubus  Chamaemorus 
Empetrum  nigrum 
N cmopanthus  mucronata 


Cornus  canadensis 
Andromeda  glaucophylla 
Chamaedaphne  calyculata 
Gaultheria  procumbens 
Gaylussacia  dumosa 
Kalmia  angustifolia 
Kalmia  polifolia 
Ledum  groenlandicum 
Rhododendron  canadense 
Vaccinium  Oxycoccus 
Vaccinium  pennsylvanicu m 
Solid  ago  uliginosa 


16  Ganong  remarks  (’98,  pp.  138,  139),  that  these  sphagnum  hummocks 
grow  “in  such  rounded,  radiating  masses  that  it  reminds  one  of  the 
Raoulia  or  ‘Vegetable  Sheep,’  and  the  resemblance  is  yet  closer  when, 
by  drying,  it  assumes  a grayish  color.” 


Vegetation  of  Northern  Cape  Breton. 


447 


It  will  be  seen  from  the  above  list  that  nearly  half  the  vascular 
species  here  are  ericaceous  shrubs  or  semi-shrubs,  and  these 
also  comprise  the  greater  bulk  of  the  vascular  plant  cover. 
Herbaceous  plants  are  subordinate  in  importance  to  shrubs, 
although  a few  forms,  such  as  Scirpus , Eriophorum  and  Ruhus, 
commonly  occupy  quite  a prominent  position.  The  various  seed 
plants  form  a thin  upper  story  of  vegetation,  but  for  the  most 
part  they  rise  less  than  a foot  above  the  mossy  substratum  and 
quite  commonly  their  shoots  are  buried  nearly  to  the  tip  by  the 
sphagnums.  The  trees  are  scattered  and  dwarfed : specimens  of 
tamarack  scarcely  a foot  high  and  an  inch  in  trunk  diameter  may 
show  more  than  fifty  annual  rings.17 


17  In  this  connection  certain  further  observations  by  Ganong  (’98,  p. 
142),  equally  applicable  to  Cape  Breton  bogs,  are  of  sufficient  interest 
and  suggestiveness  to  warrant  quoting  at  length.  “Most  of  the  ericaceous 
plants  on  the  bog  have  stems  of  great  length  running  just  beneath  the 
surface,  which,  as  Warming  points  out,  is  characteristic  of  bog  plants. 
In  one,  Rubus  Chamaemorus,  I followed  a stem  over  seventeen  feet 
without  finding  an  end,  and  in  Ledum  and  Cassandra  for  lesser,  though 
considerable  distances,  also  without  finding  the  ends.  These  stems  run 
nearly  horizontally,  branch  frequently,  and  send  out  roots  at  intervals. 
The  same  stem  varies  in  thickness  in  different  parts ; is  now  thicker, 
now  thinner,  showing  a more  active  growth  at  some  times  than  at  others. 
It  is  clear,  also,  that  these  stems  are  now  alive  only  at  their  tips,  the 
under-moss  parts  being  preserved  from  decay  by  their  position.  When 
one  traces  what  appears  to  be  a clump  of  young  plants  of  Ledum  lati- 
folium,  he  often  finds  that  they  are  all  branches  of  one  plant  connected 
beneath  the  surface,  and  he  cannot  find  the  end  of  any  one  of  them; 
and  this  is  true  also  of  other  species.  The  question  now  arises,  when 
and  how  have  such  plants  started,  and  how  do  they  come  to  an  end? 
Since  the  different  branches  can  grow  on  continuously,  and,  making  their 
own  roots,  become  independent  of  one  another  and  of  the  original  plant, 
and  can  grow  upwards  continuously  with  the  growth  of  the  moss,  there 
seems  to  be  no  logical  limit  to  their  growth,  and  no  cause  for  death, 
such  as  brings  most  other  woody  perennials  to  their  end  in  other  situa- 
tions. Some  of  them  may  then  be  as  old  as  the  bog  itself,  and  thus 
would  be  amongst  the  longest  lived  of  phanerogamic  vegetation.  Yet 
a comparison  between  their  age  and  that  of  a tree,  for  example,  would 
not  be  a fair  one ; physiologically,  their  longevity  should  be  compared 
rather  with  that  of  those  lower  organisms,  which  grow  by  continuous 
fission.  This  continuous  life  of  the  bog  plants,  however,  is  pure  theory; 
its  demonstration  is  attended  with  great  practical  difficulties.  To  some 
extent  this  mode  of  growth  is  found  also  in  the  trees.  In  the  spruces 
. . . one  may  observe  how  the  moss  is  rising  and  burying  them.  As  it 


448 


George  E.  Nichols, 


Successions l relations. — Assuming  for  the  purpose  of  illustra- 
tion a nearly  level  or  gently  sloping  rock  floor,  approximately 
flat  as  a whole  but  in  detail  with  a more  or  less  irregular  surface, 
with  slight  elevations  and  depressions  but  with  no  basins  capable 
of  retaining  any  appreciable  body  of  water,  the  successive  steps 
in  the  evolution  of  a raised  bog  may  now  be  outlined.  On  an 
uneven  rock  surface  of  the  sort  under  consideration  the  pioneer 
aspect  of  the  vegetation  varies  locally.  In  the  higher,  drier 
situations  it  is  essentially  xerophytic.  Commonly  the  vegetation 
here  is  that  of  the  sedge-grass  heath  association-type,  as 
described  in  connection  with  xerarch  successions : the  ground  is 
covered  by  a carpet  of  cladonias  and  Racomitrium , and  sup- 
ports a more  or  less  luxuriant  growth  of  Scirpus  caespitosus  and 
Calamagrostis  Pickeringii,  with  a scattering  of  low  shrubs.  In 
the  lower  situations  the  vegetation  may  be  quite  similar,  but  here, 
owing  to  the  generally  more  favorable  moisture  relations,  the 
sphagnums  commonly  establish  themselves,  either  coming  in  at 
the  outset  or  later  on  replacing  the  cladonias  and  Racomitrium. 
Subsequent  changes  in  the  nature  of  the  substratum  and  in  the 
ecological  aspect  of  the  surface  vegetation  depend  very  largely 
on  the  sphagnums,  not  merely  on  their  presence  or  absence  but 
on  the  species  which  come  to  predominate.  Where  conditions 
are  such  that  none  of  the  sphagnums  are  able  to  establish  them- 
selves in  force,  any  further  changes  will  probably  conform  closely 
with  what  has  been  described  earlier  in  connection  with  xerarch 
successions.  Where  conditions  are  such  as  to  favor  the  growth 
of  the  sphagnums  and  these  assert  themselves  as  one  of  the  pre- 
dominating elements  of  the  plant  cover,  further  changes  depend 
very  largely  on  which  particular  group  of  sphagnums  gains  con- 
trol over  the  situation. 

For  the  sake  of  simplicity  there  will  be  described  a hypothetical 
example  of  what  may  be  regarded  as  the  logical  sequence  of 
association-types : a series  in  which  the  pioneer  stage  gives  way 
to  a bog  meadow,  which  becomes  superseded  by  a wet  bog,  which 
in  turn  gives  way  to  a dry  bog;  and,  in  this  connection,  various 


buries  the  lower  branches,  these  put  out  new  roots,  turn  upwards  at 
their  tips,  and  grow  as  independent  stems.  This  growth  probably,  how- 
ever, does  not  go  on  indefinitely,  since  the  trees  are  ultimately  over- 
whelmed and  destroyed  by  the  moss.” 


Vegetation  of  Northern  Cape  Breton.  449 

other  possible  lines  of  development  will  be  pointed  out.  Let  it  be 
assumed,  as  is  very  commonly  the  case,  that  the  low  spots  have 
become  colonized  by  Sphagnum  tenellnm  and  6".  Pylaisei, 
species  which  lack  the  cushion-forming  habit.  Under  these 
circumstances  the  formation  of  peat  and  the  building  up  of 
the  substratum  may  take  place  very  slowly,  being  due  very  largely 
to  the  accumulation  of  sedge  remains.  But,  even  at  that,  it 
takes  place  much  more  rapidly  in  these  lower  areas  than  on  the 
higher  ones.  As  the  layer  of  peat  in  these  lower  areas  becomes 
gradually  thicker  and  the  ground  level  is  raised  higher,  the  sur- 
face vegetation  spreads  out  laterally  and  may  override  the  higher 
areas ; and  in  this  way  there  may  originate  what  has  been 
described  above  as  a bog  meadow. 

Further  advance  beyond  the  bog  meadow  stage  of  the  succes- 
sion is  dependent  primarily,  either  directly  or  indirectly,  on  the 
activity  of  various  cushion-forming  species  of  Sphagnum. 
Wherever  conditions  are  congenial  to  the  growth  and  spread  of 
the  mesophytic  cushion-forming  species  (S.  papillosum,  S. 
magellanicum,  S.  pulchrum),  bog  meadow  may  gradually  give 
way  to  wet  bog.  Indeed  these  species  may  have  been  the 
important  ones  from  the  very  outset,  so  much  so  that  the  bog 
meadow  stage  in  the  succession  may  never  have  been  developed. 
The  factors  which  condition  the  presence  or  absence  and  the 
relative  abundance  when  present  of  these  species  of  Sphagnum 
doubtless  have  to  do  very  largely  with  the  amount  of  water 
available  throughout  the  season,  but  it  seems  likely  also,  as 
suggested  elsewhere,  that  the  difficulty  with  which  these  and 
other  species  are  able  to  invade  areas  already  occupied  by  5". 
Pylaisei  in  particular  may  be  a factor  of  considerable  importance 
as  affecting  their  establishment  on  the  surface  of  a bog  meadow. 

The  transformation  in  the  character  of  the  habitat  accomplished 
through  the  agency  of  the  mesophytic  cushion-forming  sphag- 
nums  and  the  manner  in  which  they  bring  about  the  elimination 
of  bog  meadow  or  any  other  type  of  vegetation  which  may  be 
present  is  exceedingly  interesting.  Heretofore,  in  the  case  of 
bog  meadow,  what  water  has  not  been  absorbed  by  the  compact, 
peaty  substratum  has  been  able  to  run  off  quite  unobstructed 
over  the  comparatively  smooth,  firm  surface,  with  the  result  that 
except  during  wet  periods  the  ground  at  the  surface  may  have 
been  relatively  dry.  One  of  the  essential  characteristics  of  the 


45° 


George  E.  Nichols, 


cushion-forming  sphagnums  is  their  great  ability  to  absorb  and 
retain  liquids.  But  while  this  in  itself  is  a factor  of  no  little 
significance  in  hindering  the  loss  of  water,  even  more  significant 
is  the  manner  in  which  individual  clumps  of  these  mosses  run 
together  and  form  banks  which  may  obstruct  the  drainage  to 
such  an  extent  that  in  favorable  situations,  as  on  gentle  slopes, 
the  water  may  be  dammed  back  to  form  ponds  and  pools  of 
various  dimensions.  The  degree  to  which  masses  of  sphagnums 
are  thus  able  to  hold  back  the  water  is  remarkable.  In  t\ie  boggy 
area  diagrammatically  shown  by  Fig.  65,  C,  for  example,  the 
level  of  the  water  in  the  pond  at  e is  nine  inches  higher  than  that 
at  d,  twenty-five  feet  distant ; and  the  water  level  in  pond 
d is  twelve  inches  above  that  in  pond  c,  equally  distant.  In 
another  instance  a difference  in  elevation  of  two  feet  was 
measured  between  two  water  surfaces  thirty-five  feet  apart ; 
while  in  two  other  cases  differences  in  level  amounting  respectively 
to  nearly  ten  feet  in  less  than  a hundred,  and  to  more  than  one 
foot  in  three  were  estimated.  On  the  “down-hill”  sides  of  a pond 
the  banks  of  sphagnum  rise  steeply  from  the  water’s  edge  to  a 
height  of  one,  two,  or  more  feet  above  the  pond’s  surface.  In 
one  instance  a rise  of  three  feet  within  seven  feet  of  the  water’s 
edge  (or  to  a height  of  about  five  feet  above  the  mucky  bottom 
of  the  pond)  was  noted.  It  is  obvious  that  these  ponds,  by 
retaining  much  of  the  water  which  accumulates  in  them  during 
wet  periods,  or  which  drains  into  them  from  higher  levels, 
function  as  storage  reservoirs  and  insure  to  adjoining  areas  a 
fairly  uniform  water  supply  throughout  the  season. 

Incipient  ponds  of  the  sort  just  described  are  frequently 
encountered  in  the  bog  meadow  stage  of  the  succession,  but  there 
■ they  are  usually  shallow  and  ephemeral.  It  is  in  the  wet  bog 
stage  that  they  first  attain  a position  of  ecological  importance. 
The  formation  of  ponds  hastens  the  elimination  of  the  bog 
meadow  as  a distinct  association-type,  for  their  spread  leads 
naturally  to  the  extermination  of  any  plants  which  may  have 
tenanted  the  areas  which  they  now  occupy,  except  for  the  few 
species  which  are  able  to  adapt  themselves  to  the  changed  condi- 
tions, either  by  assuming  an  aquatic  habit  (e.  g.,  Sphagnum 
Pylaisei ) or  through  their  position  above  the  water  level  (e.  g., 
tussocks  of  cushion-forming  sphagnums). 


Vegetation  of  Northern  Cape  Breton.  451 

Sometimes  these  ponds  appear  to  be  distributed  quite  indis- 
criminately over  the  surface  of  a bog  (e.  g.,  see  Fig.  65,  A)  : 
particularly  is  this  true  on  the  higher,  older  bogs.  But  in  other 
cases  their  arrangement  is  very  definite.  To  cite  a specific 
illustration  of  the  latter  sort : in  one  shallow,  approximately  flat- 
floored  valley  (similar  to  that  pictured  in  Fig.  67)  about  a 
hundred  feet  wide,  there  are  ten  of  these  ponds  within  a distance 
of  three  hundred  feet.  All  are  more  or  less  elliptical  in  outline, 
twenty  to  fifty  feet  long  by  six  to  twenty  feet  wide,  and  they  are 
arranged,  like  a flight  of  steps,  at  right  angles  to  the  long  axis 
of  the  valley  floor.  Between  the  surface  of  the  lower  pond  in  the 
series  and  that  of  the  upper  there  is  a vertical  difference  in  eleva- 
tion of  five  feet.  It  may  be  further  noted  that  the  rock  floor 
beneath  this  bog,  as  determined  by  soundings,  is  quite  even  and 
that  the  peat  is  uniformly  about  four  feet  deep,  except  around  the 
down-hill  margins  of  the  ponds  where  it  is  banked  up  higher. 
From  the  study  of  this  and  other  like  cases,  there  seems  little 
question  that  a large  proportion  of  the  ponds  associated  not  only 
with  wet  bogs  but  also  with  dry  bogs  have  originated  in  the 
manner  here  described.  The  absence  of  any  relationship  to  the 
character  of  the  underlying  topography  is  exemplified  by  ponds 
d and  e in  Fig.  65,  C. 

Leaving  for  the  moment  the  consideration  of  these  ponds,  the 
further  history  of  the  bog  as  a whole  may  be  briefly  detailed. 
Largely  through  the  activity  of  the  mesophytic  cushion-forming 
sphagnums,  the  general  level  of  the  surface  has  been  raised  and 
bog  meadow  eliminated.  These  mesophytic  sphagnums  continue 
to  predominate  and  to  build  up  the  substratum  for  a locally 
variable  length  of  time:  frequently  a wet  bog  association  may 
represent  an  edaphic  climax.  But  although  the  nature  of  the 
environment  may  be  considerably  modified  by  the  influence 
of  the  ponds  referred  to  above,  it  is  apparent  that,  as  a rule, 
sooner  or  later,  as  the  surface  rises  higher,  the  conditions  will 
become  less  favorable  for  the  mesophytic  sphagnums,  while 
at  the  same  time  they  will  become  more  favorable  for  the 
xerophytic  cushion-forming  species  (S.  fuscnm,  S.  capillaceum 
tenellum,  S.  tenerum).  As  time  goes  on,  these  latter  species, 
which  in  wet  bog  constitute  merely  a subordinate  element  in  the 
vegetation,  gradually  become  the  predominant  forms,  and  wet 


45  2 


George  E.  Nichols, 


bog  becomes  superseded  by  dry  bog.  Incidentally  it  may  be 
remarked  that,  like  the  mesophytic  forms,  the  xerophytic  cushion- 
forming sphagnums  sometimes  predominate  from  the  very  out- 
set, so  that  both  the  bog  meadow  and  wet  bog  stages  may  be 
eliminated.  On  the  higher,  drier  parts  of  a bog,  as  elsewhere 
indicated,  the  xerophytic  sphagnums  in  turn  may  give  way  locally 
to  various  lichens  and  mosses,  but  these  never  become  sufficiently 
abundant  to  constitute  a distinct  association-type. 

Throughout  the  successive  steps  in  bog  development,  as  just 
outlined,  sight  must  not  be  lost  of  the  part  played  by  various 
seed  plants.  These  fulfill  a triple  role  in  that  they  facilitate  the 
upward  growth  of  the  sphagnums  and  bind  together  the  spongy, 
otherwise  incoherent  matrix  of  sphagnum  remains,  beside  con- 
tributing in  varying  degree  to  the  bulk  of  the  deposit.  Much  of 
the  springiness  and  comparative  firmness  which  characterizes 
the  surface  of  a mature  bog  is  ascribable  to  the  tangle  of  stems 
and  roots  with  which  the  ground  is  interwoven.  With  regard 
to  the  rate  at  which  the  bog  surface  is  built  upward : in  general, 
upward  growth  is  comparatively  slow  at  first,  during  the  bog 
meadow  stage,  most  rapid  during  the  wet  bog  stage  and  during 
the  early  part  of  the  dry  bog  stage,  from  which  point  on  there 
is  a gradual  slowing  down  until,  in  the  case  of  the  older,  higher 
bogs,  growth  is  practically  at  a standstill  (but  see  quotation  from 
Weber  on  p.  456). 

From  the  observations  recorded  in  the  preceding  pages  it  is 
apparent  that  not  only  do  the  sphagnums  as  a class  play  an  all- 
important  part  in  the  development  of  raised  bogs,  but  that  differ- 
ent groups  of  sphagnums  are  responsible  for  different  phases  in 
the  development.  It  is  also  certain  that  the  formation  and 
upward  growth  of  a bog  is  not  dependent  on  the  presence  of  any 
preexisting  water  basin  from  which  the  required  water  is  raised 
by  capillarity.  The  view  expressed  by  Ganong  (’98,  p.  148)  that 
“The  raised  bogs  are  formed,  as  all  students  of  them  agree,  by 
the  pure  Sphagnum  growing  upward  and  carrying  the  water  by 
capillarity  with  it”  has  long  since  been  exploded.  To  quote  from 
Warming  (’09,  pp.  200-201)  : “It  is  erroneous  to  suppose  that 
Sphagnum  sucks  up  water  from  the  soil ; it  raises  water  only 
for  an  inconsiderable  distance.  The  movement  of  water  in  a 
Sphagnum-moor  is  essentially  a descending  one.  The  depth  at 
which  the  water-table  lies  is  dependent  on  the  atmospheric  precipi- 


Vegetation  of  Northern  Cape  Breton.  453 

tation  and  upon  the  permeability  of  the  peat  and  of  the  sub- 
stratum   [A  raised  bog  (high-moor)]  often  arises  on 

top  of  old  low-moor;  it  may  also  take  origin  on  wet  sand,  and 
even  on  rocks  if  these  be  sufficiently  wet.”  Incidentally,  it  is 
worthy  of  note  that  although  he  accepted  the  then  current  con- 
ception as  to  the  origin  of  raised  bogs,  Ganong  was  puzzled  by, 
and  commented  at  some  length  on,  the  “presence  of  much  stand- 
ing water  near  the  surface  on  the  higher  parts”  of  the  New 
Brunswick  bogs  which  he  studied  (’98,  p.  148). 

In  this  connection,  it  is  also  of  interest  that  Ganong  (’98,  p. 
1 51)  describes  as  occurring  on  the  slopes  of  one  of  these  bogs  “a 
series  of  remarkable  holes  ....  of  various  sizes,  from  30  by  12 
feet  down  to  a few  inches.  They  are  a foot  or  two  deep,  have 
perfectly  level  bottoms  of  black  muck,  sometimes  so  dry  as  to 
crack  in  the  sun,  in  others  moist,  in  others  covered  with  water, 
the  latter  being  at  the  lower,  the  former  at  higher  levels.” 
Obviously  these  are  the  ponds  or  pond  holes  which  have  been 
discussed  at  some'  length  by  the  author.  In  northern  Cape 
Breton  also,  the  water  in  many  of  them  disappears  during  a dry 
season,  but  many  of  them  are  several  feet  deep  and  apparently 
always  contain  water.  The  ponds  on  the  higher  parts  of  a bog 
are  usually  more  or  less  circular  in  outline  (Fig.  69)  and 
ordinarily  have  steep  banks  all  around.  They  may  be  relatively 
few  in  number,  but  commonly  there  are  several  or  many  to  the 
acre.  In  many  of  them,  save  for  various  algae,  vegetation  is 
sparse  and  any  filling  in  is  accomplished  through  the  gradual 
encroachment  of  the  banks.  In  others  there  is  a luxuriant 
growth  of  aquatic  sphagnums  (S.  Pylaisei,  S.  cuspidatum) . As 
regards  the  growth  of  these  aquatic  sphagnums,  the  discrepancy 
between  different  ponds  is  hard  to  account  for,  unless,  as  is  very 
likely  the  case,  it  be  correlated  with  the  abundance  of  algae  (see 
next  paragraph).  With  the  exception  of  Nymphaea  and 
Eriocaulon,  aquatic  seed  plants  are  usually  scarce.  In  general, 
the  ecological  relations  of  the  vegetation  here  approximate  what 
has  been  described  earlier  (see:  association-complexes  of 

undrained  ponds,  p.  417;  also,  development  of  raised  bogs  in 
and  around  water-filled  rock  basins,  p.  438). 

Weber,  in  his  paper  on  the  vegetation  and  origin  of  the 
Augstumal  Hochmoor  in  Prussia  (’02,  pp.  76-78),  has  made  some 
important  observations  regarding  the  origin  of  these  ponds 


454 


George  E.  Nichols, 


(“ Hochmoorteiche Previous  investigators  for  the  most  part 
had  reasoned  either  that  they  represent  the  remains  of  lakes 
which  formerly  existed  in  the  areas  now  occupied  by  bog,  or,  in 
view  of  the  common  paucity  here  of  sphagnums,  that  they 
represent  places  where  springs  of  lime-carrying  water  break 
through,  a view  which  was  somewhat  doubtfully  favored  by 
Ganong.  Parenthetically  it  may  be  suggested  that  the  luxuriance 
with  which  the  sphagnums,  particularly  5".  Pylaisei,  not  infre- 


Figure  69. — Pools  on  surface  of  mature  raised  bog;  Scotchman’s 
Barren. 

quently  occupy  such  ponds  in  northern  Cape  Breton  is  of  relevant 
interest  in  this  connection.  In  discussing  their  origin,  Weber 
points  out  that  while  undoubtedly  the  first  explanation  mentioned 
above  is  sometimes  the  correct  one,  the  second  one  is  largely 
based  on  insufficient  investigation.  He  effectually  disposes  of 
this  lime  theory  by  making  careful  analyses  of  the  water  in  the 
ponds,  which  he  finds,  like  that  in  surrounding  parts  of  the  bog, 
to  be  extremely  poor  in  inorganic  salts.  He  therefore  concludes 
that  the  source  of  water  supply  cannot  come  from  the  ground. 
He  incidentally  comments  on  the  universal  lack  of  any  positive 
sig'ns  of  springiness,  an  observation  which  the  writer  can  con- 


Vegetation  of  Northern  Cape  Breton.  455 

firm.  Weber’s  explanation  of  the  manner  in  which  these  ponds 
usually  arise  is  somewhat  as  follows.  They  originate  in  the  pools 
of  water  which  collect  in  the  deeper  hollows  between  the  hum- 
mocks on  the  surface,  during  wet  seasons.  During  the  dry 
season  the  water  collects  here  only  temporarily,  but  long  enough 
to  permit  the  existence  of  a number  of  low  algae.  The  develop- 
ment of  algae  has  a detrimental  effect  on  the  growth  of  any 
sphagnums  which  may  be  present,  since  {op.  cit.  p.  28)  when  the 
water  dries  up  they  form  a thin  parchment-like  coat  which  over- 
grows the  sphagnums  and  cuts  off  their  light  supply.  When,  in 
times  of  increased  precipitation,  the  hollows  fill  up  with  water, 
wave  activity  brings  about  the  enlargement  of  the  basin,  while  by 
its  mere  weight,  which  in  general  is  greater  than  that  of  an 
equal  volume  of  water-soaked  peat,  the  water  contained  in  the 
basin  causes  the  pond  to  deepen,  an  end  which  is  also  favored 
through  the  increasingly  active  circulation  of  oxygen  through 
the  water.  He  further  remarks  that  while  during  subsequent 
dry  periods  numerous  pools  become  overgrown  again,  in  other 
cases  the  pools  persist  and  become  deeper  as  the  surrounding 
surface  of  the  bog  rises  higher.  He  consequently  regards  the 
deepest  pools,  in  general,  as  the  oldest  ones. 

Broadly  speaking,  Weber’s  explanation  as  to  the  origin  of 
these  ponds  roughly  approximates  that  arrived  at  independently 
by  the  writer.  The  essential  points  of  both  views  are  (/)  the 
subsequent,  rather  than  antecedent,  origin  of  the  ponds  with 
reference  to  the  bog;  (2)  the  meteoric,  rather  than  telluric, 
source  of  the  water  supply.  The  chief  point  of  difference  is  this. 
According  to  the  author’s  explanation,  the  ponds  originate  at  a 
rather  early  stage  in  the  bog’s  history  and  by  their  presence 
exercise  an  important  influence  on  its  development.  Moreover, 
after  their  preliminary  period  of  growth,  there  is  little  if  any 
subsequent  enlargement,  but  rather  the  tendency  is  just  the 
reverse.  According  to  Weber’s  explanation,  the  ponds  may 
originate  even  on  the  surface  of  the  mature  bog.  Moreover 
they  are  constantly  tending  to  increase  in  size.  So  far  as  the 
raised  bogs  of  northern  Cape  Breton  are  concerned,  it  is  the 
opinion  of  the  author  that  the  majority  of  the  ponds  to  be  found 
on  mature  raised  bogs  have  had  a history  essentially  similar  to 
what  he  has  described.  But  it  also  seems  very  likely  that  some 
and  quite  possible  that  many  of  them  may  have  originated  in 
the  manner  suggested  by  Weber.  At  any  rate,  the  writer  agrees 


453 * * 6 


George  E.  Nichols, 


with  Weber  that  even  a mature  raised  bog  is  far  from  being  in 
a condition  of  permanent  equilibrium.  To  quote  Weber  {op.  cit., 
pp.  77-78)  : “Die  Teiche  sind  nach  alledem  ebenso  .... 
Symptome  der  bestandigen  Veranderung,  die  die  Oberflache  des 
Hochmoores  unter  dem  wechselnden  Einflusse  erfahrt,  den  die 
Witterung  langerer  Zeitraume  auf  die  Vegetation  und  den 
Boden  ausiibt.  Solange  die  naturliche  Vegetation  vorhanden  ist, 
gleicht  das  Hochmoor  gewissermassen  einem  langsam  pul- 
sierenden  und  auf  die  ausseren  Einflusse  in  eigentiimlicher 
Weise  reagierenden  Organismus.” 

In  brief  summary  of  the  successional  relations  of  raised  bogs, 
as  developed  on  essentially  flat  or  undulating  surfaces,  it  may  be 
stated  that,  in  any  given  area,  there  may  ensue  a sequence  of 
stages,  starting  with  a pioneer  stage,  passing  progressively 
through  bog  meadow  and  wet  bog,  and  culminating  in  dry  bog, 
which  latter  constitutes  the  climax  stage  of  the  complete  series. 
But  the  series  is  not  always  complete.  In  an  area  occupied  by 
dry  bog,  either  or  both  of  the  preceding  stages  may  have  been 
omitted ; while,  on  the  other  hand,  either  of  these  two  stages 
may  constitute  locally  an  edaphic  climax.  The  course  of  events 
is  dependent  primarily  on  the  activity  of  certain  groups  of 
sphagnums  and  is  conditioned  by  the  presence  of  environmental 
conditions  suitable  to  their  growth.  In  the  course  of  a bog’s 
development,  through  the  activity  of  the  cushion-forming 
sphagnums,  ponds  are  formed  which,  by  conserving  the  water 
supply,  bear  a vital  relationship  to  the  bog’s  growth.  It  may  be 
added  that  the  growth  of  a bog  is  not  entirely  vertical.  As  it 
grows  upward  it  spreads  out  laterally.  A bog  originating  in  an 
edaphically  favorable  area  may  spread  out  in  all  directions, 
eventually  covering  many  ai'eas  which  of  themselves  were  not 
favorable  to  bog  development.  In  this  way,  as  has  been 
repeatedly  pointed  out,  a bog  may  invade  an  area  occupied  by 
forest  and  bring  about  the  destruction  of  the  latter.  Instances  of 
this  sort  have  been  frequently  observed  in  northern  Cape  Breton. 

3.  The  Formation-types  along  Streams 

THE  ASSOCIATION-COMPLEXES  OF  RAVINES  AND  FLOOD  PLAINS 

The  ravine  associations  of  the  hvdrarch  series  here  in  the 

highland,  like  those  of  the  xerarch  series,  require  no  special  treat- 


Vegetation  of  Northern  Cape  Breton.  457 

ment,  since  on  the  whole  the  vegetation  is  essentially  similar  to 
what  has  already  been  described  as  characteristic  of  ravines  in  the 
lowland.  Of  special  interest,  however,  are  the  association- 
complexes  of  flood  plains. 

Attention  has  elsewhere  been  called  to  the  fact  that  on  the 
plateau  most  of  the  streams  for  long  distances  flow  through 
broad,  shallow  valleys,  but  little  below  the  general  level  of  the 
surrounding  country.  The  floors  of  these  valleys  are  nearly  flat 
and  gently  inclined.  The  surface  is  only  a couple  of  feet  higher 


Figure  70. — Shallow,  flat-floored  stream  valley  with  characteristic 
vegetation ; barrens  in  mountains  west  of  Ingonish. 

than  the  water  in  the  stream  in  summer,  and  at  times  of  high 
water  it  is  subject  to  overflow.  At  such  times  a small  amount 
of  sediment  is  deposited,  and  this,  together  with  the  inundation 
itself,  apparently  has  a decisive  effect  on  the  character  of  the 
vegetation.  It  therefore  seems  appropriate  to  regard  such  areas 
as  flood  plains,  although  they  differ  in  a great  many  respects 
from  ordinary  flood  plains.  The  mineral  substratum  is  com- 
monly overlain  by  a layer  of  peat  one  or  more  feet  in  thickness, 
which  is  rendered  distinctly  gritty  by  the  fine  sediment  which 

Trans.  Conn.  Acad.,  Vol.  XXII  25  1918 


45^  George  E.  Nichols,  Vegetation  of  Northern  Cape  Breton. 

is  infiltrated  throughout  the  mass.  The  surface  vegetation  is 
essentially  that  of  a well-drained  swamp.  Over  considerable 
areas  its  ecological  aspect  is  that  of  a meadow,  with  sedges  and 
grasses  predominating.  But  as  a rule  these  swales  or  “hay 
marshes”  alternate  with  equally  extensive  patches  of  alder  thicket 
and  swampy  woodland  (Fig.  70).  Similar  associations  are 
encountered  frequently  around  the  small  lakes  which  lie  along 
the  courses  of  the  streams.  Here  all  intergradations  occur 
between  typical  well-drained  swamps  and  bogs.  Along  the 

streams  themselves  it  is  only  occasionally  that  patches  of  bog  are 
encountered,  even  the  plants  peculiar  to  bogs  commonly  being 
absent.  In  the  barrens,  where  especially  these  flat-floored 
valleys  constitute  a prominent  topographic  feature,  the  flood 
plain  vegetation  here  contrasts  sharply  with  that  of  swamps 
remote  from  stream  activity.  In  this  connection  it  is  worthy  of 
note  that  the  species  of  Sphagnum  which  play  such  an  important 
role  in  bog  development  are  scarce  or  absent  here,  although 
certain  other  species  of  Sphagnum,  e.  g.,  5'.  Girgensohnii,  S. 
recurvum,  and  palustre,  together  with  such  mosses  as 
Chrysophynum  stellatum  and  Drepanocladus  fluitans,  are  com- 
monly represented,  though  never  developing  in  any  great 
luxuriance.  A list  of  characteristic  vascular  plants  follows  : 


Osmunda  Claytoniana 
Abies  balsamea 
Picea  mariana 
Picea  canadensis 
Larix  laricina 
Agrostis  hyemalis 
C alamagrostis  canade n si s 
Glyceria  canadensis 
Scirpus  caespitosus 
Carex  stellulata 
Carex  crinita 
Carex  aquatilis 
Carex  pauciflora 
Carex  polygama 
Carex  oligosperma 
Carex  folliculata 
Juncus  sp. 


Iris  versicolor 

Habenaria  dilatata 

Myrica  Gale 

Alnus  incana 

Spiraea  latifolia 

Pyrus  arbutifolia  atropurpurea 

Amelanchier  sp. 

Rosa  nitida 
Viola  pallens 
Kalmia  angustifolia 
Chamaedaphne  calyculata 
Lonicera  caerulea 
Viburnum  cassi noides 
Solidago  uliginosa 
Solidago  rugosa 
Aster  radula 
Aster  umbellatus 


SUMMARY 


Cape  Breton  is  situated  northeast  of  the  peninsula  of  Nova 
Scotia.  In  northern  Cape  Breton  two  topographic  regions 
can  be  distinguished:  the  Highland  and  the  Lowland.  The 
highland  includes  primarily  the  lofty  interior  plateau,  which 
rises  to  an  average  elevation  of  more  than  a thousand  feet  and  is 
underlain  by  crystalline  rocks  of  Laurentian  age.  In  places  this 
extends  clear  to  the  sea,  but  along  much  of  the  coast  there  is  an 
intervening  border  of  Carboniferous  lowland,  of  varying  width, 
between  the  highland  and  the  shore.  The  entire  area  has  been 
glaciated,  drift  being  encountered  on  all  sides  in  the  lowland 
but  much  less  frequently  on  the  plateau. 

The  climate  of  the  region  as  a whole  may  be  classed  as  cool 
temperate  maritime.  The  climate  of  the  plateau  differs  from 
that  of  the  lowland  in  the  lower  mean  temperatures,  greater 
daily  range  of  temperature,  shorter  growing  season,  heavier 
precipitation,  and  generally  lower  humidity,  this  latter  being 
attributable  in  large  measure  to  the  prevalence  of  low-lying  cloud 
banks. 

Considered  from  a phytogeographical  point  of  view,  Cape 
Breton  lies  near  the  northern  border  of  the  Transition  Forest 
Region  of  eastern  North  America.  In  northern  Cape  Breton, 
owing  chiefly  to  the  differences  in  climate  mentioned  above,  both 
the  Deciduous  Forest  Climatic  Formation  and  the  Northeastern 
Evergreen  Coniferous  Forest  Climatic  Formation  are  well 
represented,  the  former  in  the  lowland,  the  latter  in  the  high- 
land. These  formations,  as  developed  in  northern  Cape  Breton, 
are  treated  separately. 

The  scheme  adopted  in  classifying  the  plant  associations  of 
these  two  regions  is  outlined  in  the  table  of  contents  and  has 
been  discussed  in  some  detail  in  another  paper  (Nichols  T7). 

The  regional  climax  association-type  in  the  lowland  is  a mixed 
deciduous-evergreen  forest,  comprising  sometimes  a dozen  differ- 
ent trees,  of  which  the  following  species  are  most  characteristic : 
Fagus  grandifolia,  Acer  saccharum,  Betula  lutea , Abies  balsamea, 
Tsuga  canadensis,  and  Finns  Strobus.  All  of  these  trees  grow 
vigorously  and  to  good  size.  The  woody  undergrowth  in  the 
forest  includes,  as  the  commoner  species,  Acer  spicatum  and 
A.  pennsylvanicnm,  Taxus  canadensis  and  Corylus  ro strata. 


460 


George  E.  Nichols, 


Thirty-fiye  herbaceous  vascular  plants  are  listed  as  characteristic. 
Bryophytes  are  present  in  profusion,  but  on  the  forest  floor  they 
are  sparsely  developed.  This  latter  fact  apparently  is  correlated 
with  the  annual  accumulation  on  the  ground  of  a blanket  of 
fallen  leaves  which  prevents  the  development  of  a moss-carpet. 

The  permanency  of  this  type  of  forest  is  indicated  by  the  com- 
position of  the  younger  generation  of  trees,  which,  in  general, 
conforms  with  that  of  the  mature  stand.  In  this  connection  the 
ecological  status  in  these  forests  of  the  balsam  fir,  character  tree 
of  the  northeastern  evergreen  coniferous  forest  climatic  forma- 
tion, is  considered  in  some  detail.  The  conclusion  is  reached 
that  the  inability  of  this  tree  to  compete  successfully  with  the 
trees  which  characterize  the  deciduous  climax  forest  formation 
can  be  attributed  very  largely  to  its  shorter  tenure  of  life, 
coupled  with  its  greater  susceptibility  to  fungus  diseases  and 
possibly  with  its  less  pronounced  tolerance  of  shade. 

The  trees  w'hich  characterize  forests  of  the  regional  climax 
type,  not  only  here  but  elsewhere  in  the  Transition  Region,  can 
be  divided  into  five  groups:  ( A ) Deciduous  species  whose  center 
of  distribution  lies  south  of  the  transition  region;  ( B ) 
Deciduous  species  whose  center  of  distribution  lies  within  the 
transition  region;  (C)  Evergreen  species  whose  center  of  dis- 
tribution lies  within  the  transition  region ; ( D ) Evergreen  species 
whose  center  of  distribution  lies  north  of  the  transition  region ; 
(£)  Deciduous  species  whose  center  of  distribution  lies  north 
of  the  transition  region.  With  reference  to  the  presence  or 
absence  of  representatives  of  the  first  four  groups  above  specified, 
eleven  floristically  different  types  of  forest  are  distinguishable 
(see  p.  292).  In  general,  the  trees  of  groups  B and  C are 
about  equally  well  represented  in  forests  throughout  the 
transition  region,  those  of  group  A are  most  generally  repre- 
sented southward,  those  of  group  D northward.  In  many  parts 
of  the  transition  region  black  spruce  replaces  balsam  fir  as  the 
predominant  northern  conifer.  Black  spruce  does  not  appear  to 
be  specifically  distinct  from  red  spruce.  It  is  very  doubtful 
whether  the  various  floristic  subdivisions  of  the  transition  region 
that  have  been  defined  should  be  regarded  as  ecologically  distinct. 
From  the  standpoint  of  ecological  plant  geography  the  vegetation 
of  the  transition  region  as  a whole  is  best  treated  merely  as  a 
northward  extension  of  the  deciduous  forest  climatic  formation. 


Vegetation  of  Northern  Cape  Breton.  461 

The  regional  climax  association-type  in  the  highland  is  pre- 
dominantly coniferous,  Abies  balsamea  being  by  far  the  most 
abundant  tree.  Associated  with  this  in  the  forest,  but  always  of 
subordinate  importance,  grow  Picea  canadensis,  P.  mariana, 
Betula  alba  papyrifera,  and  Pyrns  americana.  Ten  shrubs  and 
twenty-seven  herbaceous  vascular  plants  are  listed  as  charac- 
teristic. Bryophytes  develop  luxuriantly  on  the  forest  floor, 
forming  an  almost  continuous  ground  cover. 

The  permanency  of  this  type  of  forest  is  attested  by  the 
character  of  the  younger  growth  which  is  essentially  similar  to 
that  of  the  mature  trees.  AJ1  of  the  climax  trees  grow  best  in 
the  open  and  reproduction  is  most  prolific  in  openings  of  the 
forest  due  to  windfall.  But  the  reproduction,  at  least  of  the 
balsam  fir  and  black  spruce,  is  by  no  means  confined  to  wind- 
fall areas,  which  seems  to  be  the  case  farther  inland,  as  on  Isle 
Royale. 

That  the  coniferous  forest  climax  of  the  highland  is  a climatic 
and  not  an  edaphic  climax  is  evidenced  by  the  gradual  transition 
from  deciduous  to  coniferous  forest  encountered  in  ascending 
the  mountains,  and  by  the  practically  complete  absence  on  the 
plateau,  even  in  edaphically  favorable  situations,  of  the  climax 
trees  of  the  deciduous  forest  climatic  formation. 

A detailed  review  of  the  character  and  successional  relations 
of  the  various  association-types  which  comprise  the  edaphic 
formation-complexes  of  the  lowland  and  highland  respectively 
will  not  be  attempted  here.  An  outline  of  these  is  afforded  by 
the  table  of  contents,  at  the  beginning  of  the  paper,  and  by  the 
paragraph  headings  which  are  scattered  through  the  text. 

By  way  of  brief  general  summary  it  may  be  stated  thatrln  the 
lowland,  associations  of  the  regional  climax  type  represent 
the  culmination  of  successional  series  in  all  edaphically  favorable 
situations.  _jllsewhere  succession  stops  at  a stage  less  mesophytic 
than  the  regional  climax  association-type : in  other  words,  in 
such  situations  the  edaphic  climax  association-type  does  not 
coincide  with  the  regional  climax  association-type,  as  it  does  in 
the  more  favorable  situations.  Due  largely  to  human  activity 
many  areas  formerly  occupied  by  forests  of  the  regional  climax 
association-type  are  now  occupied  by  associations  of  a much 
more  primitive  character,  notably  by  forests  of  white  spruce  and 
balsam  fir.  In  the  lowland  the  regional  climax  forests  of  the 


462  George  E.  Nichols,  Vegetation  of  Northern  Cape  Breton. 

highland  are  represented  in  successional  series,  in  favorable 
situations  being  destined  to  give  way  to  forests  of  the  deciduous 
type  but  in  many  unfavorable  situations  constituting  edaphic 
climaxes. 

In  the  highland  the  same  general  relations  hold  true  as  in  the 
lowland  between  associations  of  the  regional  climax  type  and 
those  which  are  more  primitive.  But  here,  owing  mainly  to  the 
humidity  of  the  climate,  the  influence  of  dissimilar  edaphic  condi- 
tions is  less  pronounced  than  in  the  lowland.  It  can  be  stated 
in  general  that  the  influence  of  soil  and  topography  on  the 
character  and  distribution  of  plant  associations  is  least  pro- 
nounced in  humid  climates,  most  pronounced  in  arid  climates : 
that  this  influence  is  universally  proportional  to  the  dryness  of 
the  climate. 

The  barrens  represent  an  edaphic  association-complex,  the 
character  of  the  vegetation  being  correlated  with  conditions  of 
exposure,  topography  and  soil.  Of  especial  interest  here  is  the 
extensive  development  of  heath  and  of  various  types  of  scrubby 
forest  and  of  raised  bogs.  Particular  attention  is  called  to  the 
important  part  played  in  the  development  of  the  latter  by  different 
species  of  Sphagnum. 


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9 


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AUG  2 0 'bJ 

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Oct  t fe  bi 

oct  z - -g6 

Form  335— 40M— 6-39— S 

